How can I check the outgoing HELO name of my sendmail server?
Solution 1:
It is typical for all mail providers to log the HELO/EHLO parameter in all mail they process.
Open the headers (source) of a mail that anyone recently accepted from your server in question, it likely spells out your EHLO in one of the Received: headers. The topmost Received header mentioning your IP will contain two names: first the name you provided in HELO/EHLO, and the one obtained from looking up your network address. Usually the one next to the address literal [IP] is is rDNS name.
Received: from localhost.localdomain
(mx7.yourdomain.example [192.0.2.2])
by example.net (Postfix)
with ESMTPS
id ABC12345
for <[email protected]>; 21 Nov 1997 10:05:43 -0600
The relevant specification of what mail servers should put there is found in RFC 5321 Section 4.4
When an SMTP server receives a message for delivery or further
processing, it MUST insert trace ("time stamp" or "Received")
information at the beginning of the message content [..]The FROM clause, which MUST be supplied in an SMTP environment, SHOULD contain both (1) the name of the source host as presented in the EHLO command and (2) an address literal containing the IP address of the source, determined from the TCP connection.
Do note that some list complaining about you using a bad name does not necessarily mean the server you are currently configuring used that name. You or a previous owner of your network address could theoretically have connected to a system reporting to that list operators via other clients.
Do also note that a list operator claiming a high number of requests about a network address is a very bad sign. List operators expect that their blocks lead the affected party to thoroughly investigate before even thinking of requesting removal from the list. Be sure to confirm that the listing indeed was meant for you, specifically (e.g. see IPv6 specific explanations here) and you have firmly established that the problem has been pinpointed and fully resolved.