What is the best email sending speed to avoid spam folders and how does reputation affect it?

Key findings

• Reputation dependence: There is no single best email sending speed, as it is entirely dependent on your sender reputation with each mailbox provider.
• Warming is key: New IP addresses or domains require a slow and steady increase in sending volume (warming) to build trust and recognition with internet service providers (ISPs).
• Engagement matters: Once a sender's reputation is established, inbox placement is primarily driven by how much recipients want to receive the mail, indicated by positive engagement metrics.
• Promotions folder: For marketing emails, landing in Gmail's promotions folder is generally desirable and is not negatively impacted by sending speed.
• Negative signals: Aggressive sending practices, especially for new senders, or attempting to deceive filters (like stripping List-Unsubscribe headers), can damage your reputation and lead to spam folder placement or being added to a blocklist.

Key considerations

• Gradual ramp-up: Implement a strategic IP or domain warming plan, gradually increasing your sending volume to allow ISPs to build a positive profile for your mail. You can learn more about recommended initial email sending volumes.
• Monitor deferrals: Keep a close eye on 4xx responses, often called soft bounces. A rise in these indicates you might be sending too fast for a particular ISP, signaling a need to reduce your sending speed temporarily.
• Prioritize quality: Focus on sending relevant, wanted mail to engaged recipients. This is far more effective for long-term inbox placement than any specific sending speed strategy.
• Authenticity: Avoid deceptive tactics like trying to make bulk marketing emails appear as personal 1:1 correspondence. Such behavior can backfire and lead to emails being marked as spam or your domain appearing on a blocklist. Adhere to email sending speed best practices.

Key opinions

• Speed matters: Some marketers believe that sending speed and email headers significantly affect inbox placement, even for established senders.
• Header 'hacks': There's a belief that stripping headers, like List-Unsubscribe, can improve inbox placement by making marketing emails appear less promotional.
• Warmup importance: Marketers generally recognize that sending speed is crucial during the initial stages of building reputation with ISPs.
• Promotions folder avoidance: Some marketers actively try to avoid Gmail's promotions folder, viewing it as a lesser form of inbox placement, despite its intended purpose.

Key considerations

• Header integrity: While removing headers like List-Unsubscribe might seem like a hack for inboxing, it is considered bad practice. It signals spammy behavior and can lead to worse deliverability outcomes, as highlighted in email deliverability best practices.
• Embrace the promotions folder: For promotional mail, the Gmail promotions folder is the intended destination and should be embraced. Attempting to bypass it can backfire. Learn more about why emails go to spam.
• Authentic engagement: Focus on building a strong sender reputation through consistent, wanted mail, rather than trying to mimic 1:1 communication for bulk sends. This includes maintaining good email sending practices.

Key opinions

• Initial importance: Sending speed is most important for new email sources building their reputation with recipient ISPs.
• No universal speed: There's no single magic sweet spot for sending speed; it depends entirely on how recipients interact with your mail.
• Engagement first: If recipients like your mail, high volumes (e.g., 20,000,000/day) are acceptable; if not, no sending rate will help.
• Promotions folder is good: The Gmail promotions folder is an inbox for promotional mail. Senders should aim to be there if their content is promotional, and sending speed does not affect this classification.
• Avoid deceptive tactics: Removing List-Unsubscribe headers or trying to make bulk mail look like personal 1:1 email to avoid filters is a bad practice that can lead to spam folder placement or being added to a blocklist.

Key considerations

• Warmup strategy: New senders should ramp up slowly to give ISPs time to recognize and trust their sending patterns. This conservative approach is beneficial for building sender reputation. More information can be found on how to warm up an IP address.
• Monitor soft bounces: Closely monitor deferrals (4xx responses) or soft bounces. An increase in these metrics signals that you might be pushing sending limits at a particular ISP and should reduce volume. Suped provides tools to monitor your domain reputation.
• Authenticity over evasion: Sending legitimate bulk mail with proper headers is good practice. Deceptively trying to avoid spam filters by masquerading as personal mail or omitting standard headers will likely result in mail being flagged as spam. Understanding strategies to improve sender reputation is vital.

Key findings

• Caution with new IPs: Mailbox providers are wary of email activity from new IP addresses because spammers frequently use them to send large volumes of mail immediately.
• Gradual ramp-up: It is essential to gradually warm up IP addresses to allow mailbox providers time to assess and trust the sender's legitimacy.
• Conservative approach: Baseline warm-up approaches are often conservative, which is generally beneficial for establishing a good reputation.
• Monitor delivery responses: Monitoring deferrals (4xx responses), also known as soft bounces, is a critical indicator. An increase suggests you are pushing the ISP's limits and should reduce sending volume.
• Reputation correlation: A good sender reputation, often called a sender score, is fundamental for email deliverability and reflects how trustworthy your emails appear to Internet Service Providers.

Key considerations

• Structured warm-up: Adhere to structured IP warming schedules provided by authoritative sources to ensure new IP addresses gain trust systematically. This process directly impacts your ability to manage acceptable email sending speeds.
• Feedback loop integration: Implement and monitor feedback loops (FBLs) to understand how recipients are reacting to your mail. High complaint rates (e.g., above 0.10%) can severely damage your sender reputation, as advised in email deliverability best practices.
• Authentication standards: Properly configure and maintain email authentication protocols like SPF, DKIM, and DMARC. These are foundational for establishing domain authenticity and trust with mailbox providers, regardless of sending speed. Ensure a simple guide to DMARC, SPF, and DKIM is followed.