Summary
Bounces and phishing attacks significantly degrade email deliverability and domain reputation, as highlighted by experts, marketers, and documentation sources. High bounce rates, particularly hard bounces, signal poor list hygiene to ISPs and ESPs, leading to reduced inbox placement, potential blacklisting, and filtering. Different mailbox providers (MBPs) may treat bounces differently. Temporary failures might indicate underlying issues. Phishing attacks, domain forgeries, and the use of compromised sending addresses severely damage reputation and deliverability. Preventative measures such as SPF, DKIM, and DMARC are crucial. Regular list cleaning, suppression list management, and actively preventing phishing are essential for maintaining a positive sender reputation.
Key findings
- Bounce Rate Impact: High bounce rates, especially hard bounces, negatively impact sender reputation and deliverability, signaling poor list hygiene.
- Phishing Threat: Phishing attacks, domain forgeries, and compromised sending addresses severely damage sender reputation, leading to blacklisting and deliverability issues.
- Authentication Importance: Implementing SPF, DKIM, and DMARC is essential for preventing phishing and protecting domain reputation.
- Mailbox Provider Variation: Different mailbox providers (MBPs) may handle bounces differently, emphasizing the need for adaptable strategies.
- List Hygiene Necessity: Regular list cleaning, suppression list management, and the immediate removal of hard bounces are critical for maintaining a healthy sender reputation.
Key considerations
- Monitor Bounce Rates: Actively monitor bounce rates and investigate the causes of high bounce volumes to identify and address underlying issues.
- Implement Authentication Protocols: Implement SPF, DKIM, and DMARC to authenticate email and prevent phishing attacks.
- Practice Regular List Hygiene: Regularly clean email lists by removing hard bounces and inactive subscribers, and effectively manage suppression lists.
- Avoid Compromised Sending Practices: Avoid using sending addresses or mentioning domains associated with phishing or poor sending practices.
- Understand Mailbox Provider Policies: Stay informed about specific mailbox provider policies regarding bounces and spam complaints.
What email marketers say
13 marketer opinions
Bounces and phishing attacks significantly degrade email deliverability and domain reputation. High bounce rates, especially hard bounces, signal poor list hygiene to ISPs and ESPs, leading to reduced inbox placement and potential blacklisting. Phishing attacks using your domain directly harm your reputation, potentially resulting in blocklisting and severe deliverability issues. Different mailbox providers (MBPs) may treat bounces differently, but maintaining a clean email list and preventing phishing are crucial for a healthy sending reputation.
Key opinions
- Bounce Impact: High bounce rates, particularly hard bounces indicating invalid email addresses, are a strong negative signal to ISPs and ESPs.
- Phishing Risk: Phishing attacks utilizing a domain can lead to blacklisting and significant deliverability problems.
- List Hygiene: Maintaining a clean and up-to-date email list is critical to prevent deliverability issues related to bounces.
- Domain Reputation: Domain reputation is directly tied to how mailbox providers perceive your email program, based on metrics like bounce rates, spam complaints, and blocklist status.
- MBP Variation: Different mailbox providers may handle bounces differently, emphasizing the need for adaptable deliverability strategies.
Key considerations
- Monitor Bounces: Actively monitor bounce rates and investigate the causes of high bounce volumes.
- Clean Lists: Regularly clean email lists by removing hard bounces and inactive subscribers.
- Prevent Phishing: Implement measures to prevent phishing attacks using your domain, such as SPF, DKIM, and DMARC.
- Reputation Management: Proactively manage your sender reputation by adhering to best practices and addressing any issues promptly.
- Suppression Lists: Utilize suppression lists effectively to prevent sending emails to known bad addresses.
Marketer view
Email marketer from Email Geeks shares that some antispam systems bounce emails based on indicators (including false positives) and may track repeated sending attempts, which influences deliverability. The impact varies depending on the MBPs.
29 Aug 2023 - Email Geeks
Marketer view
Email marketer from TalosIntelligence explains that a high percentage of bad addresses can negatively affect sender reputation, leading to email blocking or spam filtering. High bounce rates are a sign of outdated or poorly maintained email lists.
27 Aug 2023 - TalosIntelligence
What the experts say
10 expert opinions
Bounces, especially high bounce rates and failures to deliver to valid addresses, negatively impact sender reputation and deliverability. Phishing attacks, domain forgeries, and the use of addresses associated with phishing (like noreply@wetransfer.com) can also severely damage reputation, leading to deliverability issues. While temporary failures may not directly harm reputation, they can signal underlying problems. Proper list hygiene, including removing addresses with 'user unknown' errors, is important. However, simply 'cleansing' a list may not significantly improve deliverability if the core issues are not addressed. Spam traps also hurt reputation. Avoiding involvement in or enabling phishing and handling bounces properly is crucial to avoid blacklisting.
Key opinions
- Bounce Impact: High bounce rates and failures to deliver to valid addresses negatively impact sender reputation and deliverability.
- Phishing Damage: Phishing attacks and domain forgeries severely damage reputation, leading to deliverability problems.
- Temp Failures: Temporary failures signal underlying problems that need attention.
- Limited Cleansing: Merely cleansing a list may not significantly improve deliverability.
- Spam Traps Matter: Hitting spam traps has a very negative impact on sender reputation.
Key considerations
- Investigate High Bounces: Investigate the causes of high bounce rates to identify and address underlying issues.
- Remove 'User Unknown' Addresses: Remove addresses with 'user unknown' errors from your mailing list.
- Avoid Phishing Associations: Avoid using sending addresses or mentioning domains heavily associated with phishing.
- Proactive Measures: Take proactive measures to prevent phishing attacks and domain forgeries.
- Handle Bounces Properly: Ensure a process is in place to handle bounced email properly.
Expert view
Expert from Email Geeks considers attempts to mail to bad addresses a negative delivery factor. Also some others that are going to affect reputation.
7 Jul 2023 - Email Geeks
Expert view
Expert from Email Geeks suggests investigating high bounces, as trying to deliver to non-existent addresses negatively impacts reputation.
5 Feb 2024 - Email Geeks
What the documentation says
5 technical articles
High bounce rates and phishing attacks negatively impact email deliverability and sender reputation. Gmail recommends keeping bounce rates below 5%. 5xx SMTP errors are more detrimental than 4xx errors. High phishing complaint volumes lead to junk folder routing or blocking. Implementing SPF and DMARC helps prevent phishing, protecting domain reputation by authenticating email and instructing mail servers on handling authentication failures.
Key findings
- Gmail Bounce Threshold: Gmail recommends keeping bounce rates below 5%.
- SMTP Error Impact: 5xx SMTP errors (permanent failures) are more damaging to sender reputation than 4xx errors (temporary failures).
- Phishing Complaint Consequences: High volumes of phishing complaints result in emails being routed to the junk folder or blocked.
- SPF Benefits: SPF records help prevent sender address forgery, a key component of phishing attacks.
- DMARC Effectiveness: DMARC protects against phishing and spoofing by authenticating email and allowing domain owners to define handling instructions.
Key considerations
- Monitor Bounce Rates: Regularly monitor bounce rates and strive to maintain them below established thresholds.
- Analyze SMTP Errors: Understand and analyze SMTP error codes to diagnose and address bounce issues.
- Reduce Phishing Complaints: Take steps to minimize phishing complaints, such as improving email authentication and content security.
- Implement SPF: Implement SPF to prevent sender address forgery.
- Deploy DMARC: Implement DMARC to protect your domain against phishing and spoofing.
Technical article
Documentation from Gmail Help explains that high bounce rates can negatively impact your sender reputation. They recommend keeping bounce rates below 5% and using feedback loops to identify campaigns causing issues. Phishing attempts originating from or impersonating your domain will lead to your domain being blacklisted, severely affecting deliverability to Gmail users.
25 Sep 2024 - Gmail Help
Technical article
Documentation from DMARC.org explains that DMARC is an email authentication protocol that helps prevent phishing and spoofing. Implementing DMARC allows domain owners to instruct receiving mail servers on how to handle emails that fail authentication checks, protecting their brand and reputation.
5 May 2024 - DMARC.org
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