We are using postfix on centos as a mail server to send out newsletters. but in the mail log file I can see that many receivers rejected our newsletters. and with the help of mxtoolbox, I found a warning message for our mail server - "reverse DNS does not match SMTP banner".
my hostname is webserver.XXXX.com that has both outgoing / incoming ip to 109.XX.XX.93, when I use reverse DNS lookup tool, the ip adress 109.XX.XX.93 resolved to webserver.XXXX.com.XX.XX.109.in-addr.arpa. Should I actually expect this to be webserver.XXXX.com, if it has to be correct? and I guess this is the case that mxtoolbox give "reverse DNS does not match SMTP banner" message?
If I telnet 109.XX.XX.93 25, i got 220 webserver.XXX.com ESMTP Postfix.