The current version of chkrootkit will throw up a warning that bindshell is INFECTED on port 465 in some circumstances when this is nothing to worry about. What it’s actually doing (in case you can’t read shell scripts, and why should you when there’s a perfectly good ‘C’ compiler available) is running netstat and filtering the output looking for ports that shouldn’t be being used. Port 465 is SMTP over SLL, and in my opinion should very definitely be used, but it is normally disabled by default.
As to whether this should worry you depends on whether you’re using secure SMTP, probably with sendmail. If you set up the server you should know this. If someone else set it up and you’re not too familiar with sendmail, the tell-tail line in the .mc file is DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s')dnl. Note the ‘s’ on the end of smtp.
Assuming you are using SMTPS, you can easily stop chkrootkit from printing an error (or returning an error code) simply by modifying the bindshell() subroutine to remove 465 from the list of ports to check. It’s on line 269 on the current, 0.49, version of the script.
I’m not so convinced that chkrootkit is any substitute for an experienced operator, but it’s out there, people use it and its better than nothing.