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SMTP HELO/EHLO Configuration Sendmail
I am using a Linux Server RHEL4 and it's getting blacklisted due to the following:
Note: xx.xx.xx.xx appeared to be suspicious because it was using the
following name to identify itself during email (port 25) connections
via the SMTP HELO/EHLO commands:
4x.4.1x.8x
How can I set my server's response or identity? I assume that it is some sendmail configuration?
Note: xx.xx.xx.xx appeared to be suspicious because it was using the
following name to identify itself during email (port 25) connections
via the SMTP HELO/EHLO commands:
4x.4.1x.8x
How can I set my server's response or identity? I assume that it is some sendmail configuration?
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With regards to PTR records, that's not the requirement.
Your mail server needs a PTR record that reverse resolves to a hostname which forward resolves (via an A record) to its IP address.
E.g. Reverse DNS and Forward DNS must both exist and match for the IP address of the mail server, and the forward DNS zone, the name must be an A record, not a CNAME.
The HELO name must be a name that resolves, and it should resolve to an IP address of the mail server, in the DNS zone, it should also be an A record, not a CNAME.
That hostname should not look like a generic name with an embedded IP address... it should look like "mail.example.com"
not "192-168-3-5.city.example.
Your mail server needs a PTR record that reverse resolves to a hostname which forward resolves (via an A record) to its IP address.
E.g. Reverse DNS and Forward DNS must both exist and match for the IP address of the mail server, and the forward DNS zone, the name must be an A record, not a CNAME.
The HELO name must be a name that resolves, and it should resolve to an IP address of the mail server, in the DNS zone, it should also be an A record, not a CNAME.
That hostname should not look like a generic name with an embedded IP address... it should look like "mail.example.com"
not "192-168-3-5.city.example.
ok you pretty much just explained what i said here:
For example, if you're sending mail from domain123.com (99.99.99.99) and they do a reverse look up on 99.99.99.99 but it comes back with something different than domain123.com, they might block your mail.
E.g. Reverse DNS and Forward DNS must both exist and match for the IP address of the mail server, and the forward DNS zone, the name must be an A record, not a CNAME.
For example, if you're sending mail from domain123.com (99.99.99.99) and they do a reverse look up on 99.99.99.99 but it comes back with something different than domain123.com, they might block your mail.
You'll have to call the ISP of the connection your mail server is on to change it.