Summary
The impact of Sendgrid MTA retries on sender reputation is complex. While some retries are normal, excessive or aggressive retries can be interpreted as spam and harm reputation. List hygiene is paramount; removing invalid addresses and handling bounces promptly are crucial. Authentication (SPF, DKIM, DMARC) and engagement (opens, clicks) can offset negative impacts. Monitoring deferral rates helps identify underlying issues. Throttling during high deferral periods and using exponential backoff are recommended. Feedback loops help address complaints, and consistent sending patterns build trust.
Key findings
- Normal Retries vs. Aggressive Retries: A normal amount of retries is generally acceptable, while overly aggressive retries can negatively impact sender reputation.
- List Hygiene is Critical: Maintaining a clean email list and promptly removing hard bounces are crucial for preventing reputation damage.
- Authentication and Engagement Matter: Proper authentication (SPF, DKIM, DMARC) and positive engagement metrics can help offset the negative effects of retries.
- Monitoring Deferral Rates is Key: Monitoring deferral rates allows for early detection of deliverability issues and helps in implementing necessary adjustments.
- Throttling is a Useful Tactic: Temporarily throttling email volume during periods of high deferral can help protect sender reputation.
Key considerations
- Implement Throttling Strategies: Develop strategies for throttling email volume when encountering high deferral rates.
- Monitor Bounce and Deferral Rates: Actively monitor bounce and deferral rates to proactively identify and address deliverability issues.
- Prioritize List Hygiene Practices: Regularly clean your email list and promptly remove invalid or inactive addresses.
- Ensure Proper Authentication: Verify that your email sending infrastructure is properly authenticated with SPF, DKIM, and DMARC.
- Focus on Content Relevance and Engagement: Create engaging, relevant content to minimize spam complaints and encourage positive user interactions.
- Implement Feedback Loops: Set up feedback loops to address complaints and reduce spam reports, improving sender reputation.
What email marketers say
10 marketer opinions
The impact of Sendgrid MTA retries on sender reputation is complex and multifaceted. While retries are a normal and expected part of email delivery, excessive or aggressive retries can negatively impact sender reputation. Several factors play a role, including deferral rates, engagement metrics, list hygiene, and authentication. Proper management of bounces, particularly hard bounces, is crucial, as is monitoring deferral rates to identify underlying issues like blacklisting. Authentication (SPF, DKIM, DMARC) and engagement (opens, clicks) can offset negative impacts, while feedback loops help address complaints and improve reputation.
Key opinions
- Normal Retries OK: A normal amount of retries is acceptable and even expected; not retrying can appear suspicious.
- Excessive Retries Bad: Excessive or aggressive retries can be interpreted as spam-like behavior, leading to blocks and a damaged reputation.
- Engagement Matters: High engagement (opens, clicks) can offset negative impacts of retries.
- Authentication is Key: Proper authentication (SPF, DKIM, DMARC) legitimizes sending and improves deliverability.
- List Hygiene Crucial: Proper handling of hard bounces and maintaining a clean list are essential to protect sender reputation.
Key considerations
- Monitor Deferral Rates: Closely monitor deferral rates to identify underlying issues like blacklisting or content filtering.
- Implement Feedback Loops: Implement feedback loops to promptly address complaints and reduce spam reports.
- Throttle When Needed: Consider throttling email volume if encountering high deferral rates to avoid overwhelming receiving servers.
- Utilize Engagement Data: Prioritize sending to highly engaged subscribers, especially during warm-up periods.
- Review Sending Practices: Review sending practices and adjust as necessary to ensure they align with best practices and ISP guidelines.
Marketer view
Marketer from Email Geeks explains that the amount of retries is normal and that an MTA not retrying a mailing can make the sending server look sketchy, as hackers tend not to retry deferrals.
21 Mar 2025 - Email Geeks
Marketer view
Email marketer from Mailjet shares that excessive retries, particularly to the same unresponsive domains, can negatively impact your sender reputation. Monitoring deferral rates and adjusting sending practices accordingly is essential.
1 Aug 2023 - Mailjet
What the experts say
2 expert opinions
Based on expert insights, Sendgrid MTA retries can damage your sender reputation if not managed carefully. Throttling email volume during high deferral periods is essential to prevent being flagged as a spammer. Unhandled bounces, potentially resulting from repeated failed retries, significantly contribute to poor reputation. Maintaining a clean, up-to-date list and promptly suppressing hard bounces are crucial to avoid ISP blocks.
Key opinions
- Throttling Protects Reputation: Temporarily reducing email volume during deferrals helps protect sender reputation by preventing excessive connection attempts.
- Unhandled Bounces Damage Reputation: Unaddressed bounces, often linked to failed retries, significantly contribute to a poor sender reputation and potential ISP blocks.
- List Hygiene is Critical: Maintaining a clean email list and promptly suppressing hard bounces are crucial for preventing reputation damage.
Key considerations
- Implement Throttling Strategies: Develop strategies for temporarily throttling email volume when encountering high deferral rates.
- Monitor Bounce Rates: Closely monitor bounce rates to identify and address issues causing delivery failures.
- Maintain List Hygiene: Regularly clean your email list by removing invalid and inactive addresses, as well as promptly suppressing hard bounces.
Expert view
Expert from Word to the Wise shares that unhandled bounces (which could result from repeated failed retries) contribute significantly to a poor sender reputation. Maintaining an up-to-date list and suppressing hard bounces is crucial to prevent ISPs from blocking your mail.
20 Nov 2023 - Word to the Wise
Expert view
Expert from Spam Resource explains that temporarily throttling email volume when encountering deferrals can help protect sender reputation. This gives receiving servers a chance to recover and prevents being flagged as a spammer due to persistent connection attempts.
21 May 2023 - Spam Resource
What the documentation says
5 technical articles
Documentation from various sources indicates that Sendgrid MTA retries can indirectly damage sender reputation if not handled properly. While Sendgrid automatically retries deferrals (temporary failures), repeated failures leading to hard bounces can negatively impact reputation. Implementing exponential backoff during retries is suggested to avoid overwhelming servers. Maintaining a clean email list by removing invalid addresses ensures retries are not wasted. High spam rates reported by users can override any retry strategy, emphasizing the need for relevant content. Consistent sending patterns, authentication, and engagement build trust, minimizing negative retry impacts.
Key findings
- Repeated Deferrals Lead to Hard Bounces: While Sendgrid retries deferrals, repeated failures can result in hard bounces, negatively impacting sender reputation.
- Exponential Backoff Recommended: Implementing exponential backoff during retries prevents overwhelming receiving servers and reduces spam flagging risks.
- List Hygiene Reduces Wasted Retries: Maintaining a clean email list ensures retries are not wasted on unreachable addresses, improving overall deliverability.
- Spam Reports Override Retries: High spam rates, regardless of retry attempts, significantly damage sender reputation. Content relevance is critical.
- Consistency Builds Trust: Consistent sending patterns, combined with authentication and engagement, build trust and minimize the negative impact of retries.
Key considerations
- Monitor Deferral and Bounce Rates: Actively monitor deferral and hard bounce rates to identify and address underlying deliverability issues.
- Implement Exponential Backoff: Ensure your retry strategy incorporates exponential backoff to avoid overwhelming receiving servers.
- Prioritize List Hygiene: Regularly clean your email list by removing invalid, inactive, and unsubscribed addresses.
- Focus on Relevant Content: Create engaging and relevant content to minimize spam complaints from recipients.
- Ensure Proper Authentication: Implement proper email authentication (SPF, DKIM, DMARC) to verify your identity and build trust with receiving servers.
Technical article
Documentation from Google Postmaster Tools explains that high spam rates reported by users can negatively impact your sender reputation, regardless of retry attempts. Focusing on list hygiene and relevant content is important.
27 Feb 2022 - Google
Technical article
Documentation from Twilio Sendgrid explains that deferrals are temporary delivery failures, and Sendgrid automatically retries these messages. Repeated deferrals might eventually lead to a hard bounce if retries fail.
30 Jun 2022 - Twilio Sendgrid
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