What is the recommended daily sending limit for an IP address?

Key findings

1. Variability: No single recommended daily limit exists due to the numerous variables involved, such as sender reputation and recipient mailbox provider policies.
2. Reputation is key: A good sender reputation allows for much higher volumes. IPs with poor reputation will face throttling or blocking at significantly lower volumes.
3. ISP-specific limits: Each ISP has its own profiling methods for traffic, which may include throttling mechanisms, especially for new or poorly reputed IPs. Understanding these is part of handling email sending rate and connection limits.
4. High volume examples: Highly reputable senders can potentially send millions of emails per day from a single IP, sometimes even millions per hour, though this is rare.
5. ESP role: Email Service Providers (ESPs) typically manage the complexities of IP sending limits and reputation on behalf of their users, incorporating built-in intelligence to optimize delivery.

Key considerations

1. IP warming: New IPs require a gradual increase in sending volume, known as IP warming, to build a positive reputation with ISPs. This means starting with very low daily volumes.
2. Dedicated IP vs. Shared IP: The need for a dedicated IP often arises when sending more than 50,000 emails monthly, though some sources suggest 250,000 emails per month for proper reputation maintenance. Otherwise, shared IPs might be more suitable, but understanding batching on shared IPs is important.
3. ESP consultation: Always consult your ESP for their specific recommendations, as their platform architecture and reputation management strategies directly impact your effective sending limits.
4. Volume vs. deliverability: Focusing solely on high volume can harm deliverability. Prioritizing engagement, list hygiene, and gradual volume increases is crucial for long-term success.

Key opinions

1. No fixed number: Many marketers agree that defining a global daily sending limit for an IP is challenging due to the numerous variables involved in email deliverability.
2. High volume potential: Experienced senders have reported clients successfully sending millions of emails per hour or even 20 million emails per day from a single IP, indicating high capacity for well-managed IPs.
3. ESP as the primary guide: It is widely recommended to consult with one's Email Service Provider (ESP) regarding specific IP sending recommendations, as ESPs often handle the underlying technical complexities.
4. Variables impact limits: Factors like traffic quality, recipient mailbox provider profiling, and IP warming significantly influence actual sending limits, more so than a generic numerical threshold.

Key considerations

1. Migration planning: When migrating to a new ESP or setting up new IPs, a comprehensive migration plan should address IP warm-up and volume distribution.
2. ESP technical limitations: While an IP can theoretically send millions, an ESP's technical infrastructure might impose practical limits, especially for sudden, large volume bursts.
3. Dedicated IP volume: If sending volumes reach around a million emails daily, considering additional dedicated IPs is often a prudent strategy to manage throughput and reputation, as explored in how many IPs are needed per million emails.
4. Reputation management: Regardless of volume, maintaining a positive sender reputation through good list hygiene and engaged recipients is paramount.

Key opinions

1. Reputation-driven: The actual number of emails an IP can send daily is primarily dictated by its established reputation with various mailbox providers. A strong reputation allows for significantly higher volumes.
2. Dynamic limits: Limits are not static but are continuously adjusted by ISPs based on real-time feedback, such as spam complaints, engagement, and bounce rates. This is part of how Gmail's bulk email sending limits are affected.
3. Warming process: For new IP addresses, a methodical warming period with progressively increasing volumes is essential to build trust with ISPs.
4. Content and recipient quality: Even with a good IP, poor email content or low-quality recipient lists can quickly degrade reputation and lead to throttling, or worse, placement on a blacklist or blocklist.

Key considerations

1. Monitoring deliverability: Continuous monitoring of key metrics (e.g., inbox placement, complaint rates, bounce rates) is vital to identify and address any issues that could impact an IP's sending capacity. Our email deliverability tester can help with this.
2. Avoiding blocklists: Sending too much volume too quickly, or sending to unengaged users, significantly increases the risk of being placed on an email blocklist (or blacklist), which severely impacts deliverability. Learn more about how your email address ends up on a blacklist.
3. Segmentation and pacing: Even with high volume, intelligent segmentation and pacing of email sends can help distribute load and maintain consistent reputation.
4. Infrastructure considerations: The underlying sending infrastructure (servers, network, ESP platform) also plays a role in how many emails an IP can efficiently handle without technical bottlenecks.

Key findings

1. General guidance, not strict limits: Documentation typically offers best practices for maintaining IP health and reputation, which indirectly dictate volume capacity, rather than stating a fixed daily limit.
2. Reputation is paramount: ISPs like Google and Microsoft publicly state that sender reputation, built on consistent good behavior and low complaint rates, is the primary factor influencing inbox placement and accepted volume.
3. Warm-up protocols: Nearly all documentation for dedicated IPs stresses the necessity of a gradual warm-up schedule, starting with low volumes (e.g., hundreds or thousands daily) and progressively increasing over weeks.
4. Dynamic throttling: Mailbox providers often implement dynamic throttling, meaning they temporarily limit incoming mail from an IP if suspicious activity or sudden volume spikes are detected, regardless of historical volume.

Key considerations

1. Compliance with guidelines: Adhering to general email sending best practices, such as proper authentication (SPF, DKIM, DMARC) and managing opt-outs, is more crucial than hitting a specific volume target. Our technical solutions for top-performing senders cover this.
2. Feedback loops: ISPs encourage senders to sign up for their feedback loops (FBLs) to receive spam complaints, enabling prompt removal of disengaged users, which in turn supports higher volume sending without triggering blocklists. This is a critical component for building a strong email reputation.
3. List quality: Documentation consistently stresses the importance of sending to engaged, opted-in subscribers to avoid high bounce rates and spam complaints, which are direct determinants of effective sending limits.
4. Segmenting traffic: For very large senders, documentation may suggest segmenting different types of email (e.g., transactional vs. marketing) and potentially using separate IPs for each to isolate reputation and manage specific traffic patterns.