Fix Yahoo Mail 5xx SMTP error codes

Author: Sam Web

5xx SMTP errors indicate an email could not be delivered due to a permanent problem. You should not retry sending email flagged with a 5xx error. Message delivery can be permanently deferred because:

You're trying to send a message to an invalid email address.

Spamhaus has your IP address listed on a Block List.

Your SMTP connection was rejected.

Your message failed authentication checks against your sending domain's DomainKeys or DKIM policy.

The message contains characteristics that Yahoo Mail won't accept for policy reasons

  1. You must be an administrator of server in order to fix the problem.
  2. If you the error is consistently appearing for more than 48-hours period and you have already given ample time to fix the error, it is best to go through the following practices when sending email through your Yahoo Mail account.
  • Have a policy for removing email addresses that result in errors/bounces.
  • Make sure to have a good email sending reputation. This is because Yahoo reviews IPs submitted for delivery issues, and based on which they may alter your reputation in their system.
  • Fill a new sender application via below mentioned link to discuss your issue.
  • However, even if you have a good email sending reputation, users can vote your email as spam, and which can affect your reputation, resulting in such errors.
  • Make sure that spammers are not abusing your email server.
  • If you using a shared IP address, mail traffic from other domains may impact your IP sending reputation negatively.
  • Make sure to consider following when you are reviewing your outgoing emails for objectionable content or practices:
  • IP address reputation
  • URL reputation
  • Sender reputation
  • Domain reputation
  • Domain Keys identified Mail (DKIM) signatures.
  • Domain-based Message Authentication, Reporting & Conformance (DMARC) authentication.

Ways to Improve your Sender Reputation

  • Follow the best practices for bulk email senders.
  • Apply for new sender status if you are a bulk email provider.
  • Know about sending limits in Yahoo Mail (on official website).
  • Review SMTP error table (on official website).
  • Make sure your emails meet industry authentication standards.
  • Review Yahoo terms for information on policies.

You're trying to send a message to an invalid email address.

Spamhaus has your IP address listed on a Block List.

Your SMTP connection was rejected.

Your message failed authentication checks against your sending domain's DomainKeys or DKIM policy.

The message contains characteristics that Yahoo Mail won't accept for policy reasons

If you the error is consistently appearing for more than 48-hours period and you have already given ample time to fix the error, it is best to go through the following practices when sending email through your Yahoo Mail account.

You're trying to send a message to an invalid email address.

Spamhaus has your IP address listed on a Block List.

Your SMTP connection was rejected.

Your message failed authentication checks against your sending domain's DomainKeys or DKIM policy.

The message contains characteristics that Yahoo Mail won't accept for policy reasons