Hosting multiple Domain/Reverse

[Stew]

We host multiple domain for email and some are having
issue sending mail(delays and NDR). I think the issue is
related to reverse dns. All of the domain's mx records
point to smpt.AnotherHostedDomain. Are there any
particular procedures in setting up reverse DNS when
hosting mail for many domains?

 

[Kevin D. Goodknecht [MVP]]

In

We host multiple domain for email and some are having
issue sending mail(delays and NDR). I think the issue is
related to reverse dns. All of the domain's mx records
point to smpt.AnotherHostedDomain. Are there any
particular procedures in setting up reverse DNS when
hosting mail for many domains?

Are all the virtual mail servers on different IP addresses?
If they are just have whomever is responsible for the reverse lookup on
those IP addresses create PTR records for those virtual servers.
If all the virtual servers are on the same IP address, the only suggestion I
can give you is to change the MX records so they all point to the same SMTP
server.
This doesn't mean that your clients will need to change the mail server name
they connect to send mail, that can be left the same. Clients do not connect
by using the MX record's SMTP server. But when your mail server connects to
another mail server to deliver mail, it should be from an IP address that
has a reverse lookup that points back to its host name.

I'll give you an example based on how I do it.
I have three SMTP servers accepting mail for ten domains, each SMTP server
has its reverse lookup pointing to its IP using its real hostname. But when
my clients connect to my SMTP server, they do it by "mail.theirdomain.com"
even though it is not the actual host name of the mail server.

 

[Jonathan de Boyne Pollard]

S> All of the domain's mx records point to smpt.AnotherHostedDomain.

Where your published DNS data say your SMTP Relay servers are is irrelevant.

S> Are there any particular procedures in setting up reverse DNS
S> when hosting mail for many domains?

How many domains you provide SMTP Relay service for is irrelevant.

Your issue (if it _is_ your issue - you haven't quoted any error messages from
delivery status notification messages that show that it is in fact your issue)
is with _other people's_ SMTP Relay servers refusing to communicate with your
SMTP Relay _clients_.

 

[Stew]

Kevin,
All of the virtual servers point to the same ip for
mail/smtp server.
I'm assuming that the issue is when a a foreign mail
server receives a message from our "domain1" and they
attempt a reverse lookup on the ip and return another(one
of our) domain name.

 

[Kevin D. Goodknecht [MVP]]

In

Kevin,
All of the virtual servers point to the same ip for
mail/smtp server.
I'm assuming that the issue is when a a foreign mail
server receives a message from our "domain1" and they
attempt a reverse lookup on the ip and return another(one
of our) domain name.

Change all of the MX records to point to the FQDN of the mail server it uses
when it connects to other mail servers. Then create a PTR for its IP address
with that hostname.
This won't affect your clients from connecting using an alias name to send
and receive email, clients don't look for MX records.