Can I have two relay hosts for email

[Nick D'Angelo]

I am configuring a new Unix server and the question came up.

We currently forward mail to one NT relay host but can I configure two in the sendmail file?

[Kevin Wright]

I think there can be only one DS..or smart relay host defined.

[someone_4]

Hello,

It took me a while but I thought there was a way to do this and here it is.

To configure SendMail to use more then one relay, edit:

/etc/mail/sendmail.cf

file and simply specify the hosts separated by a colon with no
spaces. For example:

DShostA:hostB:hostC

SendMail will always try hostA first. If hostA does not respond,
or responds incorrectly, then SendMail will try hostB and then hostC.But it will not load balance

Richard

[Kevin Wright]

excellent, thanks Richard!

[Michael Elleby III]

Maybe this goes outside of what you were asking, but you can also modify your sendmail.cf to re-direct mail 'between' two relays instead of use one, failover to the next, etc.

I do this to balance internal mail using our standard mail system (i.e. Lotus Notes) and mail that needs to go out on the Internet (i.e. to pagers)

First, you'll need to uncomment the line that enables the mailertable function:

Kmailertable dbm -o /etc/mail/mailertable

This points to the mailertable file that you will have to construct whose contents look similar to this:

pagenet.net smtp:smtp.rev.net
imcingular.com smtp:smtp.rev.net
bellsouthips.com smtp:blsmsgims.bls.com

This way, I regulate what gets sent out of my box. There is an ITRC document that provides the procedure on creating and using the mailertable feature...

Mike-

[someone_4]

Nick
Did my suggestion work for you?

richard

[Nick D'Angelo]

Richard, it appears to have worked, although I guess I won't know until one mail server goes down.

Is there any other way to test this?

Sorry for the delay in replying as I was on holidays.

[someone_4 · Accepted solution]

Hey Nick
No problem ...
well if you really wanted to test it there are ways to bring the box "down". Maybe unplug the nick card of the first one and let it go to the 2nd one. Of if you are using only /etc/hosts comment out the entry of the first one so it cant relay to that host.

Richard

[Nick D'Angelo]

Richard,

Thanks for the helpful tip. It worked like a charm.

Nick