Sending mail from webserver to external mail server with local domain name

Question

This is an issue I've encountered several time and haven't yet found a decent solution for:

Sending an e-mail from a webserver on e.g. "domain.com", to [email protected] which is hosted on an external mail server e.g. Google Mail

In my case I always send from PHP over Apache and often on shared hosting, but I can imagine this is the same case on other frameworks.

These e-mails always seem to be delivered to the local mail server, even if I set the MX records on that server to point to the right external mail server.

A solution for this is to use an external SMTP server, but this isn't always easy when you're working with clients that either need to set-up a new e-mail account on their server and provide the SMTP details or sign-up for a third-party SMTP server.

What is the solution for this? Is there no way around SMTP?

Answer 1

Most emai/MTA server "autoconfigure" themselves. They guess list of local email domains (doimans with locally hosted mailboxes).

In sendmail case you can turn it off adding the following line in sendmail.mc:

define(`confDONT_PROBE_INTERFACES', `True')

Documentation : cf/README - confDONT_PROBE_INTERFACES

Answer 2

I have had the same issue many many times (in my case using PHP on a LAMP stack). Try/check the following.

1. If you are using cPanel or similar, set the MX records to the external mailserver (Google apps etc).
2. Set up an SPF record to allow your hosting website to send email (this way no need to configure SMTP).
3. This may not be applicable but if you are using something like phpmailer. Set the property $mail->isMail(); so it tries to use your SPF allowed local mail() function to send the email. Sorry for going off into very specific advice, but might help in your particular situation.
4. Worth checking there are not similarly named local mailboxes on your hosting box. Hope this helps!