Question Unable to deliver to gmail emails

[fd_paz]

Hi,
I have installed the latest version of Obsidian on CentOs.
Yesterday I was able to send emails to every gmail addresses, but today I saw that strangely the emails to gmail don't work.
All the emails I send to gmail addresses stay inside "Mail Queue" and don't start. The email service to other emails works.

Could someone tell me how I can solve this problem?

Thanks

 

[IgorG]

Any related error messages in Plesk maillog?

 

[fd_paz]

Hi,
here is the error message:

Mar 12 04:22:34 xxxxx postfix/smtp[47395]: D19CF306: to=<xxxx@gmail.com>, relay=alt1.gmail-smtp-in.l.google.com[209.85.233.xx]:25, delay=50668, delays=50667/0.03/0.66/0.3, dsn=4.7.28, status=deferred (host alt1.gmail-smtp-in.l.google.com[209.85.233.xx] said: 421-4.7.28 [xxx.x.x.xx      15] Our system has detected an unusual rate of 421-4.7.28 unsolicited mail originating from your IP address. To protect our 421-4.7.28 users from spam, mail sent from your IP address has been temporarily 421-4.7.28 rate limited. Please visit 421-4.7.28  https://support.google.com/mail/?p=UnsolicitedRateLimitError to 421 4.7.28 review our Bulk Email Senders Guidelines. f10si2959209lfq.170 - gsmtp (in reply to end of DATA command))

 

[IgorG]

Here is a guide how to troubleshoot it An IP address of a Plesk mail server got blacklisted. How to troubleshoot?

 

[fd_paz]

thanks