It's nice that this feature FINALLY came after such a long wait. But can it really be used? Nah... not really... It's only useful if you host a single site and are okay with the fact that it's a global server setting.
I fear, though, that we'll have to wait even longer to get what the OP actually requested: a per-domain basis feature. Yet, PLESK has the nerve to raise the prices drastically again and again with upcoming year.

I really don't understand why it takes so long to implement a feature like this, one that is practically indispensable nowadays.

Personally, I haven't had issues whitelisting email ports in AWS regions, but others might have difficulties, and some services don't even offer the possibility to get whitelisted.

Even though I have access to port 25, using a relay/smarthost for individual emails and specific domains is still a valid use case.
How is it still not possible to say:
"I want a smarthost for this single domain," or "I want to relay this single email through, say, Outlook" (which is something I've had to configure manually a few years ago)?
It would be so much easier to manage in a UI than having to do it manually and worry that the settings might get overridden by Plesk some day...

Yes please, but Admin, are you serious? it took 5 years to get noticed and replied to? If your platform was for free as in sunlight, rain and storm, sure no sweat!
But you ask license fees.

Here is the required postfix config changes for per domain relay
https://serverfault.com/questions/1017560/postfix-how-to-use-a-relayserver-just-for-a-specific-domain

It would be great if this option was available at the subscription or domain level, not for the entire server. This way, you could choose a relay system for a particular domain without penalizing the rest.

I would like to see the option to have emails sent to domains within the same server sent locally. There is no need to use a relay system for these emails that will not leave the server.

Yes

+1 must this feature set

Is that almost 9 years? this is really a must have function. Since the settings are already there in postfix, all you need is to expose the settings and don't overwrite them during updates.

It is really a headache to write emails back and forth to ISPs like AWS to open the 25 port. And they never give you useful responses to let u know why you got refused. :(

If we had this choice, why do we still need to beg them for a port open?

Disturbing this has not been implemented! 99% of ALL ISPs block port 25 from being sent from any service but their own! Maybe I am just spoiled with cPanel who dont feel like hand holding and give me the ability to setup whatever ports I want, but this should not just be an option, it should have ALWAYS been in the settings!

Changing relayhost option in Postfix will not be overwritten by Plesk.
Information gathered from Plesk ticket 402990, where an support team leader discussed this with the R & D team. In fact Plesk does only overwrite settings, which can be set via Plesk like smtp_bind_address:

Manual change of this setting will be overwritten by Plesk, because it can be managed directly from Plesk. You may change the IP address from Tools & Settings > Mail server settings > Outgoing mail mode > Send from the specified IP addresses. The selected IP will be written by Plesk into postfix configuration.

The kb article [1], which links to this uservoice entry will be updated or removed completly.

[1] https://support.plesk.com/hc/en-us/articles/360000947494-Is-it-possible-to-configure-relayhost-in-Plesk-with-Postfix-

Andoni Jareño that only is a temp solution under windows only sadly

Hi,
if you use MailEnable as mailserver with plesk, you can choose Smarthost per postoffice, tested with mailenable profesional 10.42 and two postoffice/domain with different 365 tenants.
FYI if can help somebody.
Regards, AJ.

We want SMTP RELAY to be able to work together with POSTFIX

This is a critical feature. My VPS is on GoDaddy and they require outgoing mail to go through their relay server. I'm using ISP Config (which is an open source hosting manager) on another VPS server through GoDaddy and it has relay host setup built in so I just assumed it was a normal feature. Without it neither I nor any of my clients can send emails unless I dig into the Postfix config and risk it getting broken on every update.

This is one feature required for people like me who are hosting on DO. I have been going round and round trying to successfully deliver emails without much success.

+1

+1

With various providers now blocking emails from servers within IP blocks typically used by hosting providers for VPS/Cloud servers having the option to specify smtp smarthosts (ideally on a per domain level) is becoming more important.

this is another one of those things that really bugs me... this topic was started in 2014.. it is literally ONE LINE in the postfix config

relayhost=some FQDN or IP.

why does this stuff take years to add when its in high demand.

+1

+1