Mailcow can‘t send passwort reset requests to Yahoo

luto276

I just added some new users to our mailcow server and set up password recovery via an alternative mail address. One of my coworkers uses Yahoo France and is not able to receive the password reset link. I see the following error in the Postfix logfile:

4A560C50C4: to=<username@yahoo.fr>, relay=mx-eu.mail.am0.yahoodns.net[188.125.72.74]:25, delay=1.1, delays=0.46/0.04/0.36/0.22, dsn=5.7.9, status=bounced (host mx-eu.mail.am0.yahoodns.net[188.125.72.74] said: 554 5.7.9 Message not accepted for policy reasons. See https://senders.yahooinc.com/error-codes (in reply to end of DATA command))

I checked the policy reasons and can‘t explain why I can send mails to my coworker using the same mailcow server which can‘t send the passwort reset link. Does anyone have a clue why Yahoo rejects the automatically generated mails from the server?

mlcwuser

luto276 I checked the policy reasons and can‘t explain why I can send mails to my coworker using the same mailcow server which can‘t send the passwort reset link.

Does this coworker use Yahoo as well, or another email provider?

luto276 Does anyone have a clue why Yahoo rejects the automatically generated mails from the server?

The link provided in the error messages does provide clues regarding Error code 554: https://senders.yahooinc.com/smtp-error-codes/

What are 5XX (553 and 554) permanent errors?

A 553 or 554 SMTP error indicates an email could not be delivered due to a permanent problem. Message delivery can be permanently deferred because:
- You’re trying to send a message to an invalid email address.
- Your message failed authentication checks against your sending domain’s DMARC or DKIM policy.
- The message contains characteristics that Yahoo won’t accept for policy reasons.
- Other suspicious behavior which leads Yahoo to issue a permanent rejection for your SMTP connection.
- Your IP is listed by Spamhaus. Please check with https://www.spamhaus.org.

If you consistently receive 5xx errors when sending to Yahoo, we encourage you to review our Sender Requirements & Recommendations, since 5xx errors can be a symptom of a more widespread, general problem.

You should not retry sending an email that comes back with with a 5xx error. List managers should have a policy for removing email addresses that generate 5xx errors/bounces.

So, obviously, you should make sure that the email address to which the email is supposed to be delivered actually exists and is spelled correctly. You should also make sure that your server meets all the requirements regarding PTR record, SPF, DKIM and DMARC, and that your IP address is not on any blacklists.

If you meet all the requirements and the emails still aren’t being delivered, then I’d say you need to contact Yahoo: https://senders.yahooinc.com/contact/#sender-support-request

luto276

mlcwuser So, obviously, you should make sure that the email address to which the email is supposed to be delivered actually exists and is spelled correctly. You should also make sure that your server meets all the requirements regarding PTR record, SPF, DKIM and DMARC, and that your IP address is not on any blacklists.

Well it is not me sending the mail,. but the mailcow server. by using the “password recover” function. I checked the blacklists but my server is on none of them. I resolved the problem by providing the user with a one time password. This is not optimal, but it was a solution…

mlcwuser

Have you configured a sender email address and subject in the admin UI under System > Configuration > Options > Password Settings?

Make sure the domain name you’re using in the sender address is fully set up in Mailcow and in DNS (SPF, DKIM, and DMARC). For example, use something like noreply@yourdomain.tld rather than noreply@mail.yourdomain.tld or any other random domain/subdomain, unless, of course, that subdomain or domain is properly configured.