How many emails can I send per second per IP to Gmail, Yahoo and O365?
Michael Ko
Co-founder & CEO, Suped
Published 9 Jul 2025
Updated 17 Aug 2025
9 min read
The question of how many emails you can send per second per IP to major mailbox providers like Gmail, Yahoo, and Office 365 (O365) is complex. There isn't a single, universally published per second limit. Instead, deliverability hinges on a dynamic interplay of factors, primarily your sender reputation and how recipients engage with your emails. Mailbox providers constantly adjust their acceptance rates based on these signals, meaning a limit today could be different tomorrow.
This reputation-driven approach is designed to prevent spam and ensure legitimate emails reach the inbox. Unlike a fixed pipe that can only handle a certain volume, email delivery is more like a negotiation where your trustworthiness dictates how much mail you can send, and how quickly. For senders, this means focusing on quality over sheer quantity, especially during the crucial IP warming phase.
Attempting to push too many emails too quickly, especially from a new or cold IP address, will almost certainly lead to throttling, temporary deferrals, or even permanent blocklisting (blacklisting) of your sending IP or domain. The key is to understand the underlying principles that govern these limits and adjust your sending strategy accordingly.
The nuanced nature of email sending limits
For major email providers, the concept of a fixed per second sending limit is largely theoretical for high-volume senders. Instead, these providers monitor your sending behavior over time, evaluating your sender reputation and how your recipients engage with your mail. This determines the rate at which they accept emails from your IP address or domain. A good reputation can support millions of emails per day from a single IP, while a poor one can lead to limits as low as a few thousand.
When discussing email sending limits, the focus is typically on daily or hourly volumes rather than precise per-second rates. These limits are not static. For example, some users report hitting a daily limit around 2,000-2,500 emails to Gmail before their IP is blocked, especially if the sending practices are not optimal. However, large senders with excellent reputations can vastly exceed these numbers.
The dynamic nature of these limits means that consistent monitoring of your deliverability metrics is essential. Factors such as spam complaints, high bounce rates, and low engagement can quickly reduce your sending capacity, regardless of any theoretical limits. It is a continuous process of building and maintaining trust with mailbox providers.
This fluid approach by email service providers (ESPs) means that acceptable email sending speeds and throttling are directly tied to the health of your sender reputation. It's a system designed to reward good senders and restrict bad ones, ensuring a healthier email ecosystem for all users. Focusing on consistent, positive engagement will naturally lead to higher effective sending limits.
Key factors influencing email volume
Your sender reputation is the single most critical factor determining how many emails you can send and how quickly. This reputation is built over time based on various signals that mailbox providers monitor. High engagement rates, low bounce rates, and minimal spam complaints are positive signals that build trust and allow for higher sending volumes.
Conversely, a high volume of complaints, a significant number of unknown users (bounces), or hitting spam traps will severely damage your reputation. This can lead to your emails being heavily throttled, deferred, or even blocked entirely. This applies to all major providers, including Outlook (Office 365), Gmail, and Yahoo Mail.
IP warming (or sender reputation warm up) is also crucial for new IP addresses or those that have been inactive. You must gradually increase your sending volume over time, starting with small batches to highly engaged recipients. This process allows mailbox providers to recognize your IP as legitimate and build a positive sending history. For more information on this process, refer to our guide on email sending volume limits and IP warming.
Factors for high volume
Engagement rates: Consistent opens, clicks, and replies from recipients.
Low bounce rates: Maintaining a clean list with minimal invalid addresses.
Positive feedback: Users not marking your emails as spam and adding you to contacts.
Authentication: Proper SPF, DKIM, and DMARC setup.
Factors causing throttling
High complaints: Recipients frequently marking your emails as spam.
Spam trap hits: Sending to invalid or dormant addresses used by ISPs to identify spammers.
High bounce rates: Indicating poor list hygiene.
Lack of authentication: Missing or incorrect SPF, DKIM, or DMARC records.
Daily volume benchmarks and practical thresholds
While there are no official per second limits, various sources provide general daily sending limits for different email providers. It's important to remember that these are often for personal or small business accounts and do not reflect the potential for large enterprise senders with robust reputations and dedicated IP infrastructure. For example, Gmail has a limit of 500 emails per day for typical browser-based users, and up to 2,000 per day for Google Workspace accounts.
For Yahoo Mail Plus, a daily limit of 500 emails is often cited, with a recommendation of no more than 100 recipients per email. Office 365 (O365) limits can be more generous, often allowing up to 10,000 recipients per day for Exchange Online mailboxes, although this can vary based on subscription type and specific usage patterns. Keep in mind that Microsoft has introduced new requirements for high-volume senders, focusing on strong authentication and low complaint rates.
These general figures should serve as a baseline, but true high-volume sending—into the millions daily—requires a sophisticated approach to sender reputation management and infrastructure. For instance, some providers might allow millions of emails per day from a single IP, but this is always contingent on a stellar sending history and consistent positive engagement from recipients. It is a long process to build to these levels.
For more in-depth information, you can also consult our comprehensive guide on Gmail's bulk email sending limits and how various factors influence deliverability. Understanding these nuances is key to optimizing your email program for high volume.
To achieve high sending volumes and maintain excellent deliverability, focus on building a robust and scalable email infrastructure. This often means distributing your email load across multiple IP addresses. For example, some experts recommend aiming for around 1-2 million emails per IP per day to ensure fast delivery and avoid bottlenecks, even if higher volumes are technically possible.
Infrastructure: Ensure your message transfer agents (MTAs) and queues can handle the desired speed without latency.
Load balancing: Distribute traffic across multiple IPs to mitigate risks and improve throughput.
List segmentation: Send to highly engaged segments first to build positive reputation.
The role of IP reputation and infrastructure
Even with a fantastic sending reputation, hardware and infrastructure capabilities play a significant role in how many emails you can truly send per second from a single IP. Message build times, disk space, and queue management can all become bottlenecks at scale. For example, if you send 1 million emails per day, that's roughly 11-12 emails per second on average. For 20 million, it's over 230 emails per second. These are not insignificant volumes and require robust systems to handle.
Relying on a single IP address for extremely high volumes, while sometimes possible, isn't always the best strategy. If that single IP gets blocklisted (or blacklisted) due to an unforeseen issue, your entire email program could suffer significantly. Spreading the load across multiple IPs provides redundancy and helps mitigate risks. This allows for higher overall throughput without putting excessive pressure on any one IP.
Implementing proper email authentication, such as SPF, DKIM, and DMARC, is fundamental. These protocols help mailbox providers verify that you are a legitimate sender, which is a prerequisite for good deliverability and higher sending limits. For those looking to refine their email sending strategies, our resource on email sending speed best practices provides further insights.
Example SPF recordDNS
v=spf1 include:_spf.example.com ~all
Beyond the technical configurations, continuous monitoring of your sender reputation and deliverability is vital. This proactive approach allows you to identify and address any issues, such as increasing bounce rates or spam complaints, before they significantly impact your ability to send emails. Tools for blocklist monitoring are particularly useful here.
Views from the trenches
Best practices
Maintain a pristine list of engaged recipients to foster positive sender reputation.
Implement a gradual IP warming schedule for new or cold IPs to build trust with mailbox providers.
Segment your email lists and prioritize sending to your most engaged subscribers first.
Ensure proper email authentication (SPF, DKIM, DMARC) is in place and correctly configured.
Distribute your email volume across multiple dedicated IP addresses for improved throughput and risk mitigation.
Common pitfalls
Attempting to send large volumes of emails from a new IP without a proper warming period.
Failing to monitor engagement metrics, complaint rates, and bounce rates proactively.
Ignoring mailbox provider feedback loops, which can indicate deliverability issues.
Sending to unengaged or old recipient lists, which can lead to spam trap hits and complaints.
Not having adequate infrastructure to handle message build times and queue management at scale.
Expert tips
Sender reputation is paramount. A good reputation allows for much higher sending volumes than any theoretical hard limit.
For very high volumes (millions daily), expect to use a pool of multiple IPs, not just one.
Hardware and software capabilities are just as important as reputation for achieving high 'per second' rates.
Spikes in sending volume are possible but require a well-established, consistent sending history.
It's about total daily volume accepted by the MX, not just your outbound speed.
Expert view
Expert from Email Geeks says throttling is primarily reputation-driven, meaning there isn't a simple broad answer to how many emails can be sent per second, as it depends on how engaged recipients are with your contact lists.
2023-10-12 - Email Geeks
Expert view
Expert from Email Geeks says technically there is no hard limit, as some senders are successfully delivering millions of emails per day per IP, with spikes up to 5x on busy mailing days, because ISPs generally do not limit legitimate emails.
2023-10-12 - Email Geeks
Summary
The number of emails you can send per second per IP to Gmail, Yahoo, and Office 365 is not a fixed metric. It's heavily influenced by your sender reputation, which is built through consistent positive engagement from your recipients and adherence to best practices.
While general daily sending limits exist for consumer accounts, enterprise-level senders can achieve much higher volumes by maintaining an excellent reputation, properly warming up their IPs, implementing robust authentication, and distributing their sending load across multiple IPs. Proactive monitoring and quick adaptation to deliverability signals are key to sustainable high-volume email programs. Remember, deliverability is a marathon, not a sprint, where trust is earned over time, as highlighted in Allegrow's discussion on avoiding over-sending.
Gmail, 
Yahoo, and 
Office 365 (O365) is complex. There isn't a single, universally published per second limit. Instead, deliverability hinges on a dynamic interplay of factors, primarily your sender reputation and how recipients engage with your emails. Mailbox providers constantly adjust their acceptance rates based on these signals, meaning a limit today could be different tomorrow.
Gmail before their IP is blocked, especially if the sending practices are not optimal. However, large senders with excellent reputations can vastly exceed these numbers.
Outlook (Office 365), Gmail, and Yahoo Mail.
Gmail has a limit of 500 emails per day for typical browser-based users, and up to 2,000 per day for Google Workspace accounts.
Yahoo Mail Plus, a daily limit of 500 emails is often cited, with a recommendation of no more than 100 recipients per email. 
Office 365 (O365) limits can be more generous, often allowing up to 10,000 recipients per day for Exchange Online mailboxes, although this can vary based on subscription type and specific usage patterns. Keep in mind that Microsoft has introduced new requirements for high-volume senders, focusing on strong authentication and low complaint rates.
