[rt-users] Question about SMTP in an upgrade from 4.0 to 4.2

[Tim Wiley]

On 10/31/2013 01:27 PM, Alex Vandiver wrote:
> On Thu, 2013-10-31 at 16:16 -0400, Chris Hall wrote:
>
>> If I'm reading this right, am I to understand that after the upgrade
>> I'll no longer be able to send mail out via an external smtp server?
>> Is there any way around that?
>
> The "smtp" setting could cause silent mail loss.  Specifically, because
> it attempts to deliver immediately, and only once, if the outgoing mail
> server is unavailable at the moment RT attempts to send mail, that mail
> would be dropped.  The "smtp" option also did not support all of the
> core mail-sending features that the "sendmailpipe" method allows.
>
> The correct solution is to install a local MTA, which can be configured
> to relay the mail to the original SMTP host.  This provides a durable
> mail spool in case the remote SMTP server is inaccessible.  The local
> MTA does not need to be configured to accept mail locally if that is not
> how you wish RT to operate.
>   - Alex
>

To go a bit further with this, look into nullmailer.  It's a simple MTA 
for machines that *should* be able to send mail via an SMTP host, but 
*should not* receive mail.