Shared IP vs Dedicated IP
A decision framework for choosing between shared IP pools and dedicated IPs in email sending infrastructure. Shared IPs give pre-warmed reputation from a pool at the cost of shared dependency on other senders; dedicated IPs give full reputation control at the cost of needing to build it from zero through warming. The common wrong answer is assuming dedicated IPs are automatically better — Mailflow Authority's practitioner quote is worth remembering: "If you don't know how to manage IP reputation, avoid blacklists, and handle spam complaints, a dedicated IP will hurt you worse than shared. You'll burn it faster than you can warm it up." This page covers the volume thresholds where each makes sense (50,000 to 300,000 emails per month minimums depending on provider), warming timelines (14 to 45 days typical), cost economics, reputation isolation trade-offs, and honest guidance on when shared pools beat dedicated and vice versa. Data verified April 2026 against Mailtrap, Email Industries, Twilio SendGrid, Customer.io, Mailflow Authority, Prospeo and AWS SES managed IP documentation.
What shared and dedicated IPs actually mean
A shared IP address is used by multiple senders simultaneously, with reputation managed as a collective pool by the email service provider. Your sending behavior contributes to the pool's aggregate reputation, and the pool's aggregate reputation affects your deliverability. You get the benefit of pre-warmed reputation from other senders' established patterns, and you accept the risk that other senders' mistakes can temporarily affect your results. The provider typically handles most of the operational monitoring — if a spam complaint spike occurs from one sender in the pool, the provider's anti-abuse team responds rather than leaving it to you to manage.
A dedicated IP address is assigned exclusively to one sender. All email traffic from that IP originates from your sending program alone. Your reputation is shaped entirely by your sending behavior, list quality, engagement patterns, and sending consistency — there are no other senders to blame or credit. The trade-off is that you start with zero reputation history, which mailbox providers interpret as uncertain rather than trustworthy. Building trust requires warming: starting at low daily volumes and gradually increasing over 14-45 days while monitoring receiver responses for reputation signals. Mishandled warming produces worse outcomes than the shared pool would have delivered.
The conceptual shift that matters: shared IPs trade control for convenience and pre-warmed reputation; dedicated IPs trade convenience for control and reputation-isolation. Neither is universally better. The right answer depends on volume, sending consistency, operator expertise, and what the sending program is optimizing for.
When shared IP pools are the right answer
Shared IPs are the default and sufficient answer for most sending profiles. The cases where shared is genuinely better than dedicated aren't edge cases — they're the majority of real-world sending programs. Understanding these cases accurately prevents the common mistake of over-engineering toward dedicated IPs in scenarios where they hurt more than they help.
Sending volume under 50,000 emails/month
Below 50,000 emails/month, dedicated IPs generate insufficient reputation signal for mailbox providers' algorithms to profile your sending behavior reliably. The IP sits in uncertain-reputation territory where deliverability fluctuates unpredictably. Shared pools at this volume benefit your sending by providing the established reputation that your own volume can't sustain. Twilio SendGrid's guide: "A dedicated IP is only recommended if you are sending more than 50,000 emails each month."
Irregular or seasonal sending patterns
Dedicated IPs need consistent weekly volume to maintain reputation. Senders with irregular patterns — quarterly newsletters, seasonal campaigns, event-driven outreach — can't sustain the consistency dedicated IPs require. Shared pools absorb volume variability because the aggregate pool volume remains consistent even when individual senders' contributions fluctuate. For campaign-based or seasonal programs, shared pools are not a compromise — they're the structurally correct answer.
Low operator expertise on deliverability
Dedicated IPs require active reputation monitoring, engagement-signal analysis, warming schedule adjustments based on receiver responses, and incident response when reputation issues surface. Teams without dedicated deliverability resources often mismanage dedicated IPs in ways that damage reputation faster than shared pools would have. Shared pools outsource the operator expertise to the provider. The practitioner quote: "If you don't know how to manage IP reputation, avoid blacklists, and handle spam complaints, a dedicated IP will hurt you worse than shared."
Pure transactional with predictable profile
Password resets, order confirmations, account alerts, receipts — sending profiles where engagement is predictable (users expect these emails and interact with them), bounce rates naturally stay below 2%, complaint rates stay below 0.05%, and sending volume correlates directly with user activity. Shared pools at this profile perform excellently because the sending shape is exactly what receivers want to see. Postmark's 98.7% inbox placement on shared pool pricing from hackceleration.com's January 2026 test demonstrates what well-managed shared-pool transactional can achieve.
Budget-constrained early-stage sending
Dedicated IPs at $24.95-$59/month per IP plus the operator time to manage them represent a meaningful cost floor for early-stage programs. Shared pools have no per-IP cost, and the operator time is absorbed by the provider. For startups or growth-stage programs where sending-infrastructure cost matters relative to revenue, shared pools produce better deliverability-per-dollar than dedicated IPs until volume justifies the additional investment.
Mailflow Authority's 85-90% observation
Mailflow Authority reports that "85-90% of cold emailers run on shared IP infrastructure. That's not because they're lazy — it's because shared IPs are genuinely the right call for most sending volumes. The math is straightforward. Shared IPs come pre-warmed with established reputation. You don't need to spend 4-6 weeks nursing an IP from zero. You plug in, start your warmup sequences, and you're sending within days." The observation applies to more than cold email — most transactional and marketing programs benefit from shared pools below certain volume thresholds.
When dedicated IPs are the right answer
Dedicated IPs become the correct choice when specific operational needs make shared-pool structure the binding constraint. These cases are less common than the shared-pool cases above but are real and consequential when they apply. The common thread: dedicated IPs are about control and isolation, not about being automatically better.
Consistent sending over 100,000 emails/month
Above 100,000 emails per month consistently, dedicated IPs generate enough reputation signal for mailbox providers to profile your sending reliably. At this volume, your own reputation matters more to ISPs than the shared-pool aggregate, and the pre-warmed benefit of shared pools diminishes. The threshold isn't absolute — some senders sustain dedicated IPs at 20,000-50,000 per month with operational care, others need 200,000+ per month to avoid reputation inconsistencies at Microsoft Outlook.com specifically.
Reputation isolation from other senders
Shared pools mean dependency on other senders' behavior. For brand-critical sending — financial services transactional, healthcare notifications, regulatory compliance notifications, time-sensitive security alerts — isolating reputation from other senders' potential mistakes is structurally required. Dedicated IPs eliminate the external-risk dimension entirely. The cost premium is justified by the eliminated dependency.
Separate streams needing separate reputation
Sending programs with multiple distinct streams — transactional, marketing, cold outreach, broadcast — benefit from reputation separation. A complaint spike on marketing shouldn't affect transactional password-reset delivery. A broadcast failure shouldn't harm regulatory-notification reputation. Multiple dedicated IPs allocated per stream isolate these risks. Authorize Hosting's SMTP Relay includes 10 IPs at entry tier specifically to enable this segmentation pattern from day one.
Subdomain isolation requirements
DMARC policy architectures often require separate subdomains for different sending purposes (mail.example.com for transactional, marketing.example.com for promotional, outbound.example.com for prospecting). Each subdomain benefits from its own dedicated IP to align DMARC reputation with subdomain-level sender identity. Shared pools dilute this alignment because multiple subdomains from multiple customers share the same IP reputation.
Compliance requirements for IP control
Some regulatory frameworks require specific control over sending infrastructure — direct IP ownership or long-term lease, ability to audit sending behavior per IP, separation from shared-pool risks as a compliance obligation. These requirements are not about deliverability optimization but about compliance-auditable sending infrastructure. For teams under these constraints, dedicated IPs are not a choice but a requirement.
Cold email and prospecting programs
Cold email sending has a different reputation profile than transactional or opt-in marketing — higher bounce rates from list decay, lower engagement rates from recipients who didn't explicitly subscribe, higher complaint risk from recipients not expecting the email. Mixing cold email into a shared pool harms other senders in the pool; this is why shared-pool providers like Brevo explicitly prohibit cold email and why dedicated IPs for prospecting are the correct structure. Authorize Hosting's Cold Email Infrastructure product uses dedicated IPs with isolated reputation segmentation specifically for this operational profile.
The essential comparison at a glance
Twenty dimensions of comparison across reputation model, volume thresholds, warming, cost, control and operational overhead. Data verified April 2026 against Twilio SendGrid, Mailtrap, Email Industries, Customer.io documentation, Mailflow Authority, Prospeo February 2026, and Mailchimp dedicated-IP guidance.
| Dimension | Shared IP Pools | Dedicated IPs |
|---|---|---|
| Reputation ownership | Shared across all senders in the pool; collective behavior determines the pool reputation | Exclusive to single sender; sole ownership of reputation based on individual sending behavior |
| Initial reputation | Pre-warmed via pool aggregate; ready to send immediately | Zero reputation; requires warming over 14-45 days before production volume |
| Minimum sending volume | No minimum — any volume from occasional to high works | 100,000 emails/month typical minimum; 50,000 absolute floor; 20,000 with documented inconsistencies |
| Provider threshold examples | Included default on most ESPs | Postmark 300K/mo hard gate; Twilio SendGrid 50K/mo recommended; Customer.io 50K/week |
| Maximum per-IP volume | Pool capacity scales with provider infrastructure; not customer-visible | 2M/day optimal per IP; 3-8M/day technically possible on tuned infrastructure |
| Warming timeline | Not required — pool is already warmed | 14-28 days operator-led; 30-45 days customer-managed; 4-6 weeks cold email |
| Warming schedule pattern | Not applicable | Start at 20-50 emails/day, increase 20-30% weekly, monitor engagement between steps |
| Cost structure | No per-IP cost; bundled in base plan | $24.95-$59/month per IP typical; bundled in plan at some providers (Authorize Hosting includes 10 from €399/mo) |
| Re-warmup triggers | Not applicable | Volume drops below 20,000/week for 4+ weeks (Postmark documented); sustained drops below 100K/mo |
| Reputation isolation | None — dependent on all pool senders' behavior | Complete — no external dependency on other senders |
| Risk from other senders | Moderate — pool-wide spam events can affect your delivery temporarily | Zero — your sending is the only signal receivers evaluate |
| Operational overhead | Low — provider handles monitoring and anti-abuse response | Moderate-to-high — reputation monitoring, warming schedule, incident response required |
| Best-fit sending profile | Irregular volumes, transactional with predictable engagement, early-stage programs, budget-constrained | Consistent high-volume, brand-critical sending, compliance requirements, separate-stream isolation needed |
| Best-fit team profile | Teams without dedicated deliverability expertise; product teams where email is infrastructure not operational focus | Teams with deliverability engineering capacity; operators who want reputation control as a competitive advantage |
| Cost savings vs alternative | $300-$3,600/year saved vs dedicated (Smartlead data for cold email) | Higher cost justified by control and isolation; ROI depends on volume and use case |
| Authentication setup complexity | Low — provider-managed SPF and DKIM keys typically | Moderate — custom PTR records, branded return-path, custom DKIM keys possible |
| Subdomain isolation support | Limited — shared with other pool customers' subdomains | Full — subdomain-to-IP alignment possible for DMARC architecture |
| Compliance auditability | Provider-level audit; customer sees aggregate pool metrics | Direct sender-level audit; per-IP sending behavior fully traceable |
| Typical providers | Most ESP entry tiers: SendGrid Essentials, Mailgun Basic, Postmark Basic, SMTP2GO, Brevo, Elastic Email | SendGrid Pro+$30/IP, Mailgun $59/IP, Postmark $50/IP+300K gate, AWS SES $24.95/IP, Authorize Hosting 10 included from €399/mo |
| Honest recommendation | Right answer for 70-80% of sending programs where volume is under 100K/month or consistency doesn't support dedicated | Right answer for programs at 100K+/month with brand-critical or multi-stream sending where reputation isolation matters |
The volume-threshold decision framework
Volume is the primary decision variable but not the only one. The framework below sequences volume first, then sending-consistency, then operator-expertise, then compliance. Each layer refines the answer.
Under 50,000 emails/month: shared pool
Below 50,000 emails per month, dedicated IPs generate insufficient reputation signal. Shared pools produce better deliverability at this volume than dedicated IPs would, regardless of operator expertise or budget. The exception: if compliance requires dedicated IP infrastructure specifically for auditability, the compliance requirement overrides volume considerations. Otherwise, stay on shared.
50,000-100,000 emails/month: evaluate carefully
The crossover zone. Shared pools still work well for most profiles. Dedicated IPs become viable if sending consistency is strong (steady weekly volume, predictable patterns) and operator expertise is available. For irregular sending at this volume, shared remains correct. For consistent sending at this volume with isolation needs, dedicated becomes defensible.
100,000-500,000 emails/month: dedicated often right
Above 100,000/month with consistent sending, dedicated IPs generate enough reputation signal for mailbox providers to profile sending reliably. The decision shifts to: do you need reputation isolation, stream separation, or compliance control? If yes to any, dedicated is the right answer. If no to all, shared still works but dedicated is now viable without hurting deliverability.
500,000+ emails/month: dedicated almost always
Above 500,000/month, dedicated IPs are almost always the right answer. Volume generates clear reputation signal, per-IP volume thresholds (2M/day optimal) justify multiple dedicated IPs for reputation isolation across streams, and the cost-per-IP becomes negligible relative to sending volume. The remaining question is how many dedicated IPs and how they're allocated across streams.
Multi-stream sending: dedicated with segmentation
When sending spans distinct streams (transactional, marketing, cold, broadcast), multiple dedicated IPs segmented per stream isolate reputation risks. One bad marketing campaign shouldn't affect password-reset delivery. One spam complaint on prospecting shouldn't damage regulatory-notification reputation. Authorize Hosting's entry tier includes 10 IPs specifically to enable this multi-stream segmentation pattern.
Cold email or prospecting: dedicated required
Cold email sending profiles (higher bounce from list decay, lower engagement, elevated complaint risk) harm shared pools in ways that providers increasingly prohibit. Brevo explicitly bans cold email, Postmark shuts down broadcast accounts, SendGrid throttles aggressively. Cold email programs require dedicated IPs with isolated reputation segmentation — this isn't an optimization, it's a structural requirement for the sending type to work.
The warming reality — why it fails and what works
IP warming is where dedicated IPs succeed or fail. A properly-warmed dedicated IP at appropriate volume delivers better than a shared pool; an improperly-warmed dedicated IP delivers meaningfully worse than the shared pool would have. Understanding what makes warming succeed is more consequential than choosing between shared and dedicated in the first place.
The warming fundamentals: start at 20-50 emails per day on the new IP, increase volume 20-30% weekly, use highly-engaged subscribers for early warming traffic, monitor receiver responses between each volume step before increasing further. The process takes 14-45 days depending on target volume, receiver behavior, and engagement quality. Rushing warming is the primary failure mode — volume spikes before receivers have had time to evaluate sending patterns trigger spam filters and reputation damage that takes months to reverse.
Email Industries' 2026 warming guidance captures the common failure modes: "Sending too much volume too soon: jumping to high volumes before mailbox providers have had time to evaluate your sending behavior triggers spam filters and can result in blocks that are difficult to lift. Sending to low-quality lists: warming with bounce-prone or unengaged lists concentrates reputation damage exactly when you're most vulnerable. Ignoring early warning signs: if engagement is declining during warming, pushing more volume accelerates the problem rather than fixing it — the answer is usually to slow down rather than speed up." Authorize Hosting's operator-led warming model addresses these failure modes through receiver-response monitoring and schedule adjustment rather than following rigid day-by-day ramps.
Authorize Hosting's dedicated IP model explained
Our dedicated IP approach differs structurally from most providers in three ways, and explaining those differences is important context for teams evaluating whether our product lines fit their sending profile. As a Swedish independent operator trading continuously since 2003, we've refined the dedicated-IP bundling model over two decades of customer deployments rather than inheriting it from an acquisition playbook.
First, IPs are bundled into plan tiers rather than billed per-IP as add-ons. SMTP Relay Starter at €399/month includes 10 dedicated IPs. Growth at €749 includes 15. Scale at €1,499 includes 20. Custom plans accommodate 50+ IPs. This is different from the prevalent $24.95-$59/IP add-on model because we're pricing the infrastructure rather than the individual IP — the plan tier determines how much sending capacity and operator engagement you get, and IPs come with the capacity.
Second, there's no monthly-volume gate on dedicated IP access. Postmark's 300K/mo minimum, AWS Managed IPs' automatic revocation below minimums, and the general industry pattern of gating dedicated IPs behind volume thresholds are absent. Teams that need dedicated IPs for reasons other than pure volume — compliance, subdomain isolation, brand-reputation protection, multi-stream segmentation — can access dedicated IPs from day one at the entry tier. The warming discipline still applies, but access to dedicated IPs is structural rather than volume-contingent.
Third, warming is operator-led rather than customer-managed. Across the 14-28 day warming window, we monitor receiver responses at Gmail, Microsoft, Yahoo Postmaster Tools, adjust daily send volumes based on engagement signals, and engage directly on deliverability questions. The alternative models — customer-managed warming via ESP dashboards, AWS Managed IPs' automated warming with minimal human oversight, or warming services sold as separate add-ons — place more operational burden on the customer. Our model places it on the operator team because warming is where dedicated IP deployments succeed or fail. For EU-based sending programs, the Stockholm-jurisdiction operation also removes the cross-border data-transfer mechanics that US-headquartered providers require customers to navigate under GDPR.
Frequently asked questions about shared vs dedicated IPs
Direct answers on the IP model decision
What's the difference between a shared IP and a dedicated IP in email sending?
A shared IP is an IP address used by multiple senders simultaneously, managed as a pool by an email service provider. Reputation on a shared IP is collective — all senders in the pool contribute to and are affected by the aggregate sending behavior. A dedicated IP is an IP address assigned exclusively to a single sender. Reputation is entirely based on that sender's behavior, with no influence from other senders. The practical difference is ownership of reputation: shared IPs give you pre-warmed reputation from the pool at the cost of dependency on other senders' behavior; dedicated IPs give you full control over reputation at the cost of needing to build that reputation from zero through warming. Shared IPs are the default for low-volume senders and many ESPs' entry tiers. Dedicated IPs are recommended when volume is high enough to sustain reputation (50,000+ emails per month minimum per Twilio SendGrid guidance, 300,000+ for Postmark dedicated IPs), when isolation from other senders matters (brand-critical sending, compliance requirements), or when separate reputation for different sending streams is required (transactional vs marketing, production vs prospecting).
When should I use a dedicated IP vs shared IP?
Use shared IPs when sending under 50,000 emails per month, when sending is irregular or seasonal, when you lack dedicated deliverability monitoring resources, or when the low-overhead of shared pool reputation outweighs the control of dedicated IP management. Use dedicated IPs when sending more than 100,000-300,000 emails per month consistently (the threshold varies by provider), when reputation isolation from other senders matters (brand-critical transactional sending, compliance requirements), when separate streams need separate reputation (transactional vs marketing vs cold outreach), when subdomain isolation is required, or when consistent sending patterns make IP reputation-building viable. Mailflow Authority's practitioner guidance: '85-90% of cold emailers run on shared IP infrastructure. That's not because they're lazy — it's because shared IPs are genuinely the right call for most sending volumes.' The volume threshold isn't a hard line — it depends on sending consistency, list quality and operator expertise — but as rough guidance, dedicated IPs below 50K/month typically hurt more than they help because insufficient volume prevents meaningful reputation from forming.
How long does IP warming take?
Typical warming timelines: 14-28 days for operator-led warming on managed services (Authorize Hosting's model), 30-45 days for customer-managed warming via ESP dashboards (Customer.io's documented range), 4-6 weeks for cold email warming (Prospeo February 2026 guidance). The timeline depends on target volume (higher target volumes take longer), receiver behavior (Gmail and Microsoft warm faster than Yahoo and AOL in most configurations), engagement quality (warming with highly-engaged subscribers is faster than with broader lists), and operator expertise (experienced warming schedules adapt to receiver responses rather than following rigid day-by-day ramps). Warming involves starting at 20-50 emails per day on the new IP and increasing 20-30% weekly, with engagement monitoring after each volume step to confirm receivers are accepting the new sending pattern. Rushing warming is the most common cause of warming failure — 'if your warming isn't working after week 2, the answer is usually to slow down rather than push harder.'
How much do dedicated IPs cost in 2026?
Price per dedicated IP varies significantly by provider in 2026. Amazon SES standard dedicated IPs: $24.95/month per IP flat rate. SendGrid dedicated IPs: $30/month per IP on Pro plan with 3 IPs included. Mailgun dedicated IPs: $59/month per IP as add-on. Postmark dedicated IPs: $50/month per IP but requires 300,000 emails per month minimum as a hard gate. SMTP2GO dedicated IPs: $25/month per IP. Dedicated SMTP providers for cold email: $25-$100+ per IP per month. Managed dedicated IP services with warming bundled: $15/month base + tiered volume fees (AWS Managed IPs), or bundled into service subscription (Authorize Hosting). Authorize Hosting model: 10 dedicated IPs included from SMTP Relay Starter at €399/month with no per-IP add-on, warming bundled, no volume gate. Scale to 15 IPs on Growth (€749), 20 IPs on Scale (€1,499), Custom plans for 50+ IPs. The price-per-IP comparison isn't as meaningful as total-cost-for-configuration comparison because providers bundle IPs differently with other service components.
Can a dedicated IP hurt deliverability?
Yes, decisively. A dedicated IP with insufficient sending volume (under 20,000 emails per month across all domains using it), inconsistent sending patterns (large gaps followed by bursts), poor list quality (high bounce rates, low engagement, spam traps), or incomplete warming is strictly worse than a shared IP for the same sending. Insufficient volume means mailbox providers don't have enough data to build a reputation profile, so the IP sits in uncertain-reputation territory where deliverability fluctuates unpredictably. Inconsistent sending signals unreliable behavior to ISPs. Poor list quality concentrates the reputation damage on your IP alone rather than diluting across a pool. Incomplete warming means receivers haven't been given a chance to learn your sending pattern before volume increases. Mailflow Authority's practitioner quote: 'If you don't know how to manage IP reputation, avoid blacklists, and handle spam complaints, a dedicated IP will hurt you worse than shared. You'll burn it faster than you can warm it up.' The implication: dedicated IPs are not automatically better — they're better when used correctly with the volume, consistency and operator expertise they require.
What's the minimum volume to maintain a dedicated IP's reputation?
Industry consensus for 2026: 100,000 emails per month is the commonly-cited figure for maintaining a healthy dedicated IP reputation. Below that, reputation signals become too sparse for mailbox providers' algorithms to assess sending habits reliably. Some senders maintain dedicated IPs at 20,000-50,000 emails per month but with documented inconsistencies particularly at Microsoft Outlook.com. Postmark's dedicated IP eligibility threshold is 300,000/month — below that, they structurally refuse to provision dedicated IPs because they know the reputation-building won't work. AWS Managed Dedicated IPs automatically revoke and route sending through shared pool if volume drops below minimums. Per-IP volume ceiling: 2 million emails per dedicated IP per day is generally advisable for optimal throughput and avoiding receiver-side throttling, though 3-8 million per day is technically possible on well-tuned infrastructure. The volume-per-IP ceiling determines how many IPs are needed for larger sending programs — a 10M/day program typically uses 5+ dedicated IPs rather than one.
How does Authorize Hosting's dedicated IP model work?
Dedicated IPs are bundled into plan tiers rather than billed per-IP with volume gates. SMTP Relay Starter at €399/month includes 10 dedicated IPs with operator-led 14-28 day warming and no monthly-volume gate — dedicated IP access is available from day one regardless of initial sending volume. Growth at €749 includes 15 IPs. Scale at €1,499 includes 20 IPs. Custom plans accommodate 50+ IPs for enterprise sending programs. The structural differences from competitor models: no 300,000-per-month gate like Postmark, no $24.95-per-IP add-on pricing like AWS SES, no 256-IP minimum like AWS BYOIP, and no complex tiered warming fees like AWS Managed IPs. Warming is operator-led rather than customer-managed: we monitor receiver responses across Gmail, Microsoft, Yahoo Postmaster Tools during the 14-28 day warming window, adjust daily send volumes based on engagement signals, and engage directly on deliverability questions. For teams whose use case genuinely needs dedicated IPs — reputation isolation, subdomain separation, compliance, brand-risk management — Authorize Hosting's model removes the volume-gate and operator-expertise friction that competitor models impose.
Should I mix shared and dedicated IPs?
Mixed configurations are the right answer more often than pure dedicated or pure shared. Common mixed patterns: transactional email on dedicated IP (volume is high enough to sustain reputation, isolation from marketing protects critical mail), marketing email on shared pool (volume is variable and shared pool absorbs bounce-rate spikes), cold email or prospecting on isolated dedicated IPs (reputation-damage protection from higher-risk sending), and broadcast or newsletter on shared pool (irregular volume not suitable for dedicated). Some senders go further with IP segmentation by campaign type — prospecting sequences on one IP block, follow-ups on another, event-driven outreach on a third. This isolates reputation damage: if a prospecting blast triggers complaints, follow-up sequences keep flowing uninterrupted. AWS Managed Dedicated IPs implement this automatically through adaptive shared-pool spillover during warming and sudden volume changes. Authorize Hosting handles mixed configurations via product-line selection: SMTP Relay for mixed sending, Cold Email Infrastructure for isolated prospecting dedicated IPs, Dedicated Email Servers for custom-configuration programs.
What happens to dedicated IP reputation during volume drops?
Three critical thresholds exist for dedicated IP reputation during volume drops. First, Postmark's explicit re-warmup trigger: below 20,000 emails per week for 4+ consecutive weeks requires full re-warmup. Second, AWS Managed Dedicated IPs: may automatically remove the dedicated IP and route through shared pool if volume falls below minimums. Third, general industry guidance: 100,000 emails per month is the commonly-cited threshold for maintaining healthy reputation; sustained drops below this threshold cause reputation to decay as mailbox providers lose confidence in the sending pattern. Operational implications for seasonal senders or campaign-based programs: (1) plan sending to maintain minimum volumes even in slow periods, (2) use shared pools for campaign-based sending where consistent volume isn't possible, (3) consolidate multiple low-volume dedicated IPs into fewer IPs at sustainable volumes, or (4) accept that dedicated IPs may need re-warming after extended low-volume periods. Authorize Hosting's operator-monitored reputation model catches volume-drift before it triggers receiver-side reputation decline, with warming guidance when sending resumes after extended slow periods.
How does the decision interact with authentication setup?
SPF, DKIM and DMARC matter regardless of IP choice, but the authentication details change between shared and dedicated. Shared IPs: SPF records point to the provider's published IP ranges (include:spf.provider.com), DKIM keys are managed by the provider on the shared infrastructure, alignment happens via return-path subdomain. Dedicated IPs: SPF can be more specific (direct IP references plus provider-managed includes), DKIM can use customer-specific keys rather than shared provider keys, reverse DNS (PTR records) must map back to sender's domain not the provider's. The operational difference is that dedicated IPs give more authentication control (branded PTRs, custom return-path, explicit IP allow-listing) but require more configuration discipline at setup. For teams whose authentication policy requires custom DKIM keys or branded reverse DNS, dedicated IPs are the structural answer. For teams where provider-managed authentication is sufficient, shared pools reduce configuration complexity. Authorize Hosting provides both options — shared-pool sending on lower-tier products for transactional-only use cases, dedicated-IP sending from entry tier at €399 for teams needing the authentication control.