Linux Server Help - Fix issue with Postfix sending out unknown e-mails
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IT Professional, Server Admin, Microsoft Certified - Mission - to satisfy my cleints
Wilmslow
141275015645255011325386449283932331105170512606731537355
Description
Experience Level: Intermediate
Estimated project duration: 1 day or less
General information for the business: Server Technical Admin Required
Description of requirements/functionality: Knowledge of SSH, Postfix and Plesk is required. Server is Linux with CentOS 7.
Something is sending messages via postfix on my server. I’m not sure where these e-mails are coming from or how to stop them. This has caused my server IP to be blocked. Please see example from mail log below. Tried adding firewall on plesk on SMTP but this ended up blocking everything from being sent/received. Made this amend to ssshd_config in SSG but did not help - 'AllowTcpForwarding no'. Unsure what else to do.
Mar 9 13:53:46 server postfix/smtpd[14724]: connect from mx02.discovery.co.za[66.155.106.182]
Mar 9 13:53:47 server postfix/smtpd[14724]: NOQUEUE: reject: RCPT from mx02.discovery.co.za[66.155.106.182]: 550 5.1.1 : Recipient address rejected: User unknown in virtual mailbox table; from=<> to= proto=ESMTP helo=
Mar 9 13:53:47 server postfix/smtpd[14724]: disconnect from mx02.discovery.co.za[66.155.106.182]
Mar 9 13:53:47 server /usr/lib64/plesk-9.0/psa-pc-remote[988]: Message aborted.
Mar 9 13:53:47 server /usr/lib64/plesk-9.0/psa-pc-remote[988]: Message aborted.
‘cleezy.co.uk’ is a domain on my server but the ‘arnav_dotson’ is unknown. There are lots of these attempting to be sent.
Also reset passwords on SSH and restricted login access to one username and my own IP.
Specific technologies required: SSH, Linux, Postfix and SMTPD knowledge, Plesk, CentOS7
OS requirements: Linux
Extra notes:
Description of requirements/functionality: Knowledge of SSH, Postfix and Plesk is required. Server is Linux with CentOS 7.
Something is sending messages via postfix on my server. I’m not sure where these e-mails are coming from or how to stop them. This has caused my server IP to be blocked. Please see example from mail log below. Tried adding firewall on plesk on SMTP but this ended up blocking everything from being sent/received. Made this amend to ssshd_config in SSG but did not help - 'AllowTcpForwarding no'. Unsure what else to do.
Mar 9 13:53:46 server postfix/smtpd[14724]: connect from mx02.discovery.co.za[66.155.106.182]
Mar 9 13:53:47 server postfix/smtpd[14724]: NOQUEUE: reject: RCPT from mx02.discovery.co.za[66.155.106.182]: 550 5.1.1 : Recipient address rejected: User unknown in virtual mailbox table; from=<> to= proto=ESMTP helo=
Mar 9 13:53:47 server postfix/smtpd[14724]: disconnect from mx02.discovery.co.za[66.155.106.182]
Mar 9 13:53:47 server /usr/lib64/plesk-9.0/psa-pc-remote[988]: Message aborted.
Mar 9 13:53:47 server /usr/lib64/plesk-9.0/psa-pc-remote[988]: Message aborted.
‘cleezy.co.uk’ is a domain on my server but the ‘arnav_dotson’ is unknown. There are lots of these attempting to be sent.
Also reset passwords on SSH and restricted login access to one username and my own IP.
Specific technologies required: SSH, Linux, Postfix and SMTPD knowledge, Plesk, CentOS7
OS requirements: Linux
Extra notes:
Alex A.
100% (7)Projects Completed
7
Freelancers worked with
7
Projects awarded
30%
Last project
27 Mar 2024
United Kingdom
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Hi Alex,
Have you been able to determine whether the emails are being accepted and delivered, or are the connection attempts all being rejected? Also, how did you find out that your mail servers have been blacklisted - are all emails being rejected or just by some hosts?
Kind Regards,
Neil
351206
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