When do email senders need more dedicated IPs?

Key findings

• Volume Thresholds: Many experts suggest considering additional dedicated IPs once daily sending volume exceeds 1 million emails, or around 2.5 million emails per day for consistent sends.
• Rate Limiting: If ISPs are consistently rate limiting your sends, it often indicates a need for more IPs to distribute the load, or a deeper reputation issue.
• Reputation Management: More dedicated IPs can offer greater control over your sender reputation, allowing you to isolate different types of mail or segments to separate IPs.
• List Quality: High-quality, consistent email lists with low complaint and bounce rates can often sustain higher volumes on fewer IPs.
• Mailbox Provider Diversity: Sending to a diverse set of mailbox providers, especially many smaller ones, may necessitate more IPs due to varying concurrent connection limits and throttling policies.

Key considerations

• Consistency of Volume: Erratic sending, particularly sporadic high-volume campaigns, can negatively impact IP reputation and may lead to throttling, even on dedicated IPs. Consistent daily volume is generally preferred.
• Content-Based Throttling: More IPs will not solve issues related to content-based rate limits (e.g., problematic URLs or domain names in your emails), which are assessed by mailbox providers after the DATA command.
• ESP Role: Your Email Service Provider (ESP) plays a crucial role in managing IP allocation and deliverability. Understand their policies and infrastructure capabilities (e.g., failover, dynamic IP pooling).
• Warm-up Process: Each new dedicated IP requires a careful warm-up period, gradually increasing sending volume to build reputation with ISPs. This is critical for new IPs and domains to establish trust. More information on this can be found at MailSoar's guide.
• Tracking Complexity: Adding more IPs can increase the complexity of tracking and managing your email performance and reputation across multiple points.

Key opinions

• Volume Benchmarks: A common rule of thumb suggests considering more than one dedicated IP if sending exceeds 2.5 million emails per day.
• High Volume on Single IP: Some marketers successfully send very high volumes, such as 78 million emails per month, on a single dedicated IP, provided the list is consistent and of high quality.
• ESP Responsibilities: Marketers question why their ESP might not prevent rate limiting or offer appropriate IP solutions for their volume, especially concerning failover capabilities.
• Control and Visibility: A desire for additional dedicated IPs often stems from wanting more control over sender reputation and better visibility into deliverability performance, rather than relying on an ESP's shared IP pool during throttling.

Key considerations

• Mixed IP Pools: Marketers generally advise against mixing dedicated and shared IP pools for the same sending stream, preferring a dedicated pool if volume warrants it.
• Speed vs. Deliverability: Adding IPs may not improve sending speed if bottlenecks are related to database processing or HTML generation, rather than ISP throttling. However, deliverability is distinct from speed, and can be improved with more IPs.
• Blocklist Visibility: A single dedicated IP can make it clearer if a client or specific IP is blocklisted, whereas issues within a large shared or dedicated pool might go unnoticed. Using blocklist monitoring helps with visibility.
• Campaign Consistency: It's challenging to send very large, infrequent campaigns (e.g., a 15 million weekly newsletter) on a single IP without experiencing deliverability challenges, highlighting the need for consistent daily volume.
• High-Volume Benefits:Dedicated IPs are recommended for businesses sending over 100,000 emails per month, as they provide better control over deliverability and allow for a more tailored reputation.

Key opinions

• Daily Volume Focus: Experts primarily evaluate IP needs based on daily email volume, not monthly or weekly, as peak daily sends are usually where issues arise. Exceeding 1 million emails per day warrants consideration for additional dedicated IPs.
• Mailbox Provider Specifics: The specific mailbox providers in a sender's database significantly influence IP requirements. More IPs are beneficial if sending to numerous smaller, potentially slower MBPs with stricter concurrent connection limits.
• Reputation is Key: Rate limiting is often a symptom of underlying reputation issues (e.g., high complaints, bounces). Addressing these core problems through list hygiene and engagement can be more effective than simply adding IPs.
• Limited Need for Many IPs: For typical email volumes, even high ones, experts often suggest that one or two dedicated IPs are sufficient, with more IPs being an edge case for specialized segmentation.

Key considerations

• Diagnostic Approach: Senders should investigate which specific ISPs are rate limiting them and if these limits are reputation-based. This diagnosis helps determine if more IPs or a different strategy is needed.
• Content-Based vs. IP-Based Issues: It's crucial to differentiate between rate limits caused by IP reputation and those triggered by email content (e.g., problematic URLs). More IPs will not resolve content-based issues.
• Metric Monitoring: Regularly checking for drops in metrics or spikes in complaints and bounces is essential for identifying reputation problems that lead to rate limits. Tools like Spam Resource provide insights into diagnosing rate limits.
• Consistent Sending: Maintaining consistent daily volume on a dedicated IP is vital. Sporadic high-volume sends can be detrimental to IP reputation, regardless of the number of IPs.

Key findings

• Control Over Reputation: Dedicated IPs provide senders with full control over their sender reputation, meaning their deliverability is solely dependent on their own sending practices, without interference from other senders.
• Volume Recommendations: Many providers suggest dedicated IPs for volumes exceeding 100,000 emails per month, or when consistently sending thousands of emails daily. The specific thresholds can vary.
• Consistency is Crucial: Dedicated IPs are most effective for consistently high volumes. Sporadic or inconsistent large sends can harm the IP's reputation and lead to throttling, even on a dedicated IP.
• Warm-up Requirement: A new dedicated IP requires a gradual warm-up period, slowly increasing sending volume over days or weeks to build trust with mailbox providers and avoid deliverability degradation.

Key considerations

• Reverse DNS: Proper reverse DNS configuration for dedicated IPs is becoming increasingly important, with some major mailbox providers, like Google, requiring it for senders above certain daily volumes (e.g., 5,000 emails per day).
• Transactional vs. Marketing: Dedicated IPs are often favored for transactional emails due to their critical nature and consistent volume, allowing for predictable deliverability. However, they can also be used for marketing sends.
• Sender Reputation Maintenance: Maintaining a healthy sender reputation on a dedicated IP requires continuous monitoring of bounce rates, complaint rates, and engagement metrics. This proactive approach helps ensure messages reach the inbox and avoid blocklisting.
• Security Control: Dedicated IPs can offer more control over email security, including the ability to implement Secure Socket Layer (SSL) encryption, further building trust with recipients.