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Our ISP blocks outbound port 25 (annoying) and we are currently paying for a relay service.

One of our clients on the server is running a high traffic website and pretty much everyone who goes on the site wants to enter the competition which in turn sends a thank you email. I don't want to stop the thank you email going out but I was wondering if its possible to change the default exim outbound port to 587 and if this would have any adverse effect on email deliverability?

I am running cPanel/WHM. Many thanks!

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closed as off-topic by EEAA, Ward, mdpc, Jacob, MichelZ Apr 28 '14 at 7:02

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions must be relevant to professional system administration. Server Fault is dedicated to professional system and network administrators. End user and enthusiast questions are off-topic (contact your system administrator or hire a professional to help you out). Please see the Help Center for more information." – EEAA, Ward, mdpc, Jacob, MichelZ
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You should not be using cpanel. Period. It is an abomination, and it is keeping you from learning the skills necessary to properly admin and troubleshoot your systems. – EEAA Apr 27 '14 at 14:32
@EEAA you are probably right but it does allow us to deploy environments much more quickly and to easily manage a majority of things. It is only areas that go above and beyond the call of duty of cPanel (which is relatively little) that can be a problem. – Chris Apr 27 '14 at 15:41
That's what a proper configuration management is for. – EEAA Apr 27 '14 at 16:25

If you're using a relayserver, i guess you use the smarthost configuration of exim. If so, then you just need to identify the routeur that takes care of routing mail to smarthost, and define a transport for this router that uses the smtp driver but on port 587:

remote_submission: driver =smtp protocol = smtp port = 587

You can also edit the default remote_smtp transport if you're sure there is no impact. Remember that submission often require authentication and tls... so you'll need to play with hosts_require_auth, passwd.client file and maybe tls options depending on server certificate.

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Thanks for the good answer. If I was to change remote_smtp: to port = 26 for example, would this require that the remote server has port 26 open too to receive the email? – Chris Apr 28 '14 at 6:50
exactly. That's the reason why you may prefer to create a new transport, unless you are all your email traffic goes to your smarthost on the submission port. (thank you to accept the answer if its good for you ;) ) – alxgomz Apr 28 '14 at 7:48

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