It started about a week ago, gmail.com started an agressive rate limiting (DEFER), seems gmail.com have serious problems regarding to all of our and customers server log.
(host alt1.gmail-smtp-in.l.google.com[188.8.131.52] said: 421-4.7.28 [xxx.xxxx.xxx.xxx 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. r7si22638516lji.136 - gsmtp (in reply to end of DATA command))
I have to mention that the unusual mails are hardly reduced due holidays and we are speaking about 5 /hr. at maximum on this server.
If I have to guess, gmail is under massive attack.
Until they fix the issues our users reported the following problems:
- Password recovery loop
- Delayed Emails
- Login Error
- Unable to send email
Related to our services, if you have gmail address registered please be patient.