0
votes
0answers
49 views

Zimbra SMTP Reverse DNS Mismatch

I have a Zimbra email server. sending and receiving is fine, however When I use online tools to check that things are configured properly, I'm being told my reverse DNS SMTP Banner is wrong. ---- ...
0
votes
2answers
340 views

Postfix: bouncing mail (reverse DNS issue)

I have a problem with Postfix. I get this with some email address: to=<mail@domain.tld>, relay=mail.domain.tld[IP_ADDRESS]:25, delay=3, delays=0/0/2.5/0.52, dsn=5.7.1, status=bounced (host ...
15
votes
5answers
367 views

Is it good practice or too draconian to reject mails from mailservers with no RDNS

I've recently dropped SpamAssassin and am now basing spam rejection on DNSRBL's, grey-listing and other basic tests and I'm wondering whether I should also block hosts that don't have a valid RDNS ...
0
votes
0answers
304 views

The HELO/EHLO string doesn't match to one of the names in the rDNS from connecting IP

I have a website that uses Postfix to send out emails. It turns out the IP address for my site has been blacklisted, and testing here: http://multirbl.valli.org/, by sending out an email results in ...
1
vote
1answer
53 views

Postfix sending emails via multiple broadband lines

I have a site that send out emails from a postfix server. They have multiple broadband lines for load balancing and failover. I want them to be able to send out emails though both lines without the ...
2
votes
1answer
934 views

Having trouble interpreting mail log DNS errors

I have a postfix mail server on Debian. A client of mine just informed me that they were unable to send an email to me and it appears that there is a problem with their mail server. I would like to ...
0
votes
2answers
2k views

How to prevent DNS lookups when service already disabled DNS lookups?

My enterprise recently deployed a DNS capability to all systems within the enterprise. Due to a fluke asynchronous routing error for some of our servers, we have discovered that even when a service ...
3
votes
2answers
345 views

Postfix & client IP reverse DNS

I explicitly added reject_unknown_client_hostname and several other reject rules to slow down SPAM in our server. So far that's working nicely. However, there is an important client that keeps ...
0
votes
2answers
2k views

Disable reverse PTR check in Zimbra and force accept from invalid domains

I've moved an older Sendmail/Dovecot system to a Zimbra community edition system. I need to be able to receive messages from certain standalone Linux hosts that may not have valid A records or proper ...
0
votes
1answer
120 views

e-mail RDNS lookup

I'm getting lots of junk "return to delivery" mail on my server, so I would like to add this "RDNS" lookup thing in Ubuntu. But I can't figure out how. Most documentation is about regular DNS ...
1
vote
3answers
950 views

Reverse DNS required to send emails

I run my own email server (postfix) and my own DNS servers (bind) on openSUSE 11.2. Lately I've found that I cannot send email to Comcast users, apparently because they cannot do a reverse DNS on my ...