I am getting rate limited from gmail because twitter is sending too much email on behalf of a client?? 4AC9447EC 96028 Sun Jan 8 20:02:04 n017563f646-d74be539b30a478fba45e3a58fb85ace-afiliacion===XXXXXXXXX.firstname.lastname@example.org (host alt1.gmail-smtp-in.l.google.com[188.8.131.52] said: 421-4.7.0 [xx.xx.xx.xx 15] Our system has detected an unusual rate of 421-4.7.0 unsolicited mail originating from your IP address. To protect our 421-4.7.0 users from spam, mail sent from your IP address has been temporarily 421-4.7.0 rate limited. Please visit 421-4.7.0 https://support.google.com/mail/?p=UnsolicitedRateLimitError to 421 4.7.0 review our Bulk Email Senders Guidelines. d11si19614840yba.242 - gsmtp (in reply to end of DATA command)) email@example.com From what I understand n017563f646-d74be539b30a478fba45e3a58fb85ace-afiliacion===XXXXXXXXXX.firstname.lastname@example.org is the sender and email@example.com is the receiver. So why is my server involved in any of this? Why is twitter sending stuff to gmail through my server?