Oracle Cloud Port 25

hisdarkmaterials23

Hi everyone,

I am currently running Mailcow on Oracle Cloud (Ubuntu VM). As you probably know, Oracle restricts outbound SMTP traffic on port 25 by default, and their official solution relies on using their Email Delivery service or customizing Postfix as described here:
https://blogs.oracle.com/cloud-infrastructure/post/why-shared-ips-are-the-right-place-to-start-with-oci-email-delivery

The problem is that Mailcow is an out-of-the-box Docker-based solution and doesn’t provide an easy way to apply the kind of Postfix customizations Oracle requires.

I’d like to ask:

Has anyone successfully integrated Mailcow with Oracle’s Email Delivery service?
Alternatively, have you found a way to make Mailcow send emails using a different port (other than 25) that works on OCI?
Or maybe there are other workarounds you are using to bypass this limitation?

Any advice or shared experience would be greatly appreciated.

Thanks a lot!

esackbauer

Why it is not possible?
Its actually quite easy to configure relayhosts, you can do it in the mailcow admin UI:
https://docs.mailcow.email/manual-guides/Postfix/u_e-postfix-relayhost/
And I think you are not bound to use Oracles Relay services, you can use others with free tiers like smtp2go as well.

friendsfan

Hope a late reply is ok, but just in case other ppl stumble on that problem as well….

You can just open a ticket with Oracle support “Request a limit increase” and ask them to open Port 25 outbound. Worked for me without any problems and no need to setup a relay host.

You have to contact them anyway most likely for setting up PTR Record for IPv4/6.

hisdarkmaterials23

friendsfan

the support replied to me that cannot open 25 port, what about PTR?

friendsfan

hisdarkmaterials23

Strange, they did it for me without any question. Did you “start” with the dedicated option “Request a limit increase” in your help Section (upper right corner questionmark symbol when you logged in)? Didi they gave an explanation why they didnt do it?

Regarding PTR: You need to set the PTR (rDNS) so your IP points to your mail Domain, otherwise your sent mails will get rejected most likely by many servers. And AFAIK only Oracle support can do this, no option to set this up yourself.

mlcwuser

hisdarkmaterials23 he support replied to me that cannot open 25 port, what about PTR?

If they won’t open port 25, then you don’t need a PTR from them either.

You have a few options:

Switch to another VPS provider and set up Mailcow there. This very likely costs money.
Set up a relay on another VPS. This usually costs less, because the relay host doesn’t need as many resources as running Mailcow directly.
Use a service like Mailgun. These services can be free up to a certain volume, but costs money once you exceed the limits.

In any case, the PTR record has to be set up for the host that actually sends the emails to other mail servers. That means Oracle would be out of the picture — they wouldn’t need to open port 25 or set the PTR record.

hisdarkmaterials23

friendsfan

i cannot setup PTR in my DNS?

thanks

friendsfan

hisdarkmaterials23

It may be possible with Oracle, i am not sure. The Network setup possibility there are way above my pay grade frankly….
So i just wrote a support ticket.

But there is a difference for sure, if you just setup a PTR Record were you manage your DNS settings for your Domain Name (which for me would be Cloudflare).

PTR needs to be set by your hoster, ISP etc., either via some Settings Option or manually with a ticket.

Maybe someone with more technical insight can explain it better…

EDIT:

From the Oracle Help Sites: https://docs.oracle.com/en-us/iaas/Content/Network/Concepts/reverse_dns.htm