Question
An IP address of a Plesk mail server got blacklisted. What to do?
Note: The following article covers cases when a local mail server is used by Plesk.
Answer
Table of Contents
- What are the symptoms if a Plesk IP address is blacklisted?
- Blacklist - what is it?
- Why an IP address got blacklisted?
- What to do if a server IP address is blacklisted?
- How to remove an IP address from blacklists?
What are the symptoms if a Plesk IP address is blacklisted?
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Mail cannot be sent to external mail addresses with a bounce message like:
Note: In the output below, the IP address 203.0.113.2 belongs to a Plesk server.
550 SC-001
(SNT004-MC4F35) 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).
[203.0.113.2] The IP you're using to send mail is not authorized to 550-5.7.1 send email directly to our servers. Please use the SMTP relay at your 550-5.7.1 service provider instead. Learn more at 550 5.7.1 https://support.google.com/mail/?p=NotAuthorizedError h1si7104782plt.44 - gsmtp (in reply to end of DATA command))
5.7.1 Service unavailable; client [203.0.113.2] blocked using
prs.proofpoint.com (in reply to RCPT TO command)
421 4.7.0 [TSS04] Messages from 203.0.113.2 temporarily deferred due to user complaints - 4.16.55.1; see https://help.yahoo.com/kb/postmaster/SLN3434.html
550 mail not accepted from blacklisted IP address [203.0.113.2] (in reply to MAIL FROM command)
MailEnable: Message could not be delivered to some recipients.
The following recipient(s) could not be reached:
Recipient: [SMTP:[email protected]]
Reason: 554 Your access to this mail system has been rejected due to
poor reputation of a domain used in message transfer
The server returned:
554 Blocked - see https://ipcheck.proofpoint.com/?ip=203.0.113.2 -
When checking a server IP address using the MXToolbox blacklist checker or https://whatismyipaddress.com/blacklist-check, it shows that the IP address is in one of the DNS-based email blacklists (Commonly called Realtime blacklist, DNSBL or RBL).
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On Windows servers with MailEnable mail server, the following entries can be found in the SMTP-Activity logfile in
%installation_path%Mail:
EnableLoggingSMTPRemote server returned a response indicating a permanent error. Server Response:(550 Mail content denied. http://mail.example.com/cgi-bin/help?subtype=1&&id=20022&&no=1000726**)
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