Allow all connections on a certain port

I am running SMTP on both origin servers behind my load-balancer, but it seems connections are not allowed through while using Cloudflare’s proxy.
SMTP connections are made when the load-balancer is in DNS-only mode, however I would like to use session affinity, which means i need to run through Cloudflare. As soon as i enable Cloudflare proxy (orange icon) then my SMTP connections cannot be made…
The easiest thing I can think of is to allow all traffic on ports 25 and 587, but i can’t see how to create a rule for this.
Any advice much appreciated!

You cannot do that. With an Enterprise plan you could tunnel SMTP, with all other plans you cannot.

So i will never be able to make SMTP connections through a load-balancer in proxy mode without upgrading to enterprise?
Is it then possible to have session affinity while the load balancer is in DNS-only mode?

Session affinity wouldn’t apply to SMTP anyway… at least not well. It’s SMTP session affinity isn’t really necessary unless you’re trying to make SMTP do something really peculiar. For that matter load balancing isn’t necessary either, set 2 mail servers to the same priority and you have ‘close enough for government work’ load balancing between them. Set another server with a higher number (lower priority) and you have failover & a spam magnet.

Source: managed 1m+ mailboxes for far too long.

And in almost every case, if you were talking to me I’d try to talk you out of spending the money if that was all you wanted to do. Plenty of 3rd party providers who provide value add (anti-spam) that obfuscate your origin IP by becoming your inbound mail gateway.

The session affinity isn’t for SMTP, it’s for regular users connecting to the same servers with their browser (port 443)
Essentially, i need my system to parse incoming mail and then display certain info to a user that’s connected to the website through a browser. With session affinity off (DNS-only mode) i get random errors and certain info isn’t reliably dispalyed. With Proxy mode, those errors disappear, but the SMTP connections aren’t being made.

Correct.

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