- Plesk for Linux
Unable to send an email from Plesk server to @gmail.com, @hotmail.com, @outlook.com, @yahoo.com or any Microsoft-hosted mailbox, due to the following error in
CONFIG_TEXT: postfix/qmgr: 9BAC3FDD6B: host ASPMX.L.GOOGLE.COM[203.0.113.2] said: 421-4.7.0 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. 91si5730706wrs.75 - gsmtp (in reply to end of DATA command)
postfix/smtp: connect to ASPMX.L.GOOGLE.COM[2a00:1450:400c:c02::1b]:25: Network is unreachable
CONFIG_TEXT: qmail: 1524715120.095054 delivery 124: failure: Connected_to_2001:db8:f61:a1ff:0:0:0:80_but_sender_was_rejected. Remote_host_said:_550_5.7.1_Unfortunately,messages_from[203.0.113.2]_werent_sent.Please_contact_your_Internet_service_provider_since_part_of_their_network_is_on_our_block_list(S3150)._You_can_also_refer_your_provider_to_http://mail.live.com/mail/troubleshooting.aspx#errors.
CONFIG_TEXT: Remote Server returned '554 5.7.1 <outlook-com.olc.protection.outlook.com #5.7.1 smtp; 550 5.7.1 Unfortunately, messages from [203.0.113.2] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3140). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors.
CONFIG_TEXT: postfix/smtp: 9AEA08CB9D: host mta6.am0.yahoodns.net[184.108.40.206] said: 421 4.7.0 [TSS04] Messages from 203.0.113.2 temporarily deferred due to user complaints - 220.127.116.11; see https://help.yahoo.com/kb/postmaster/SLN3434.
The same bounce back message may be sent to the sender informing about not successful delivery
Server IP is blacklisted as spamming on the destination server (on recipient side).
Identify the source of spam and block it:
When source of spam is found and stopped, contact the blacklist support in order to exclude server IP from their blacklist: