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

Definitely a +1 for this.

Being able to relay to an external SMTP is needed for users who provide hosting services on platforms like Digital Ocean. DO only support one rDNS record so in a shared hosting environment where many domains share a single IP, some mail providers flag email send from the domains as spam because the domain name lookup does not match the reverse lookup for the IP. As such, it's essential to be able to route through a 3rd-party (like Amazon SES, SendGrid, Mailgun, etc.).

+1

Nice to have this options +1

# in the backend: option to set at least one smarthost, ideally more, for failover, and perhaps with hourly, minute, daily limits
# in user frontend: option (enforcable) for each user to set their smarthost(s), also with limits per hour/minute/day
# option to disable all email for clients except forwarders, which should be confirmed by link click
# all of the above will help reduce spam and help to derisk server mgmt since IPs are far less in danger
# please implement yesterday ;)

Having just set up a new server with Plesk I am impressed (compared to the version I used 10 years ago) - almost everything can be done easier and quicker than doing it manually in Remote Desktop. However there are 5 or 6 things we had to change, it would be good if these could be done in Plesk (with an information button next to each feature to explain it). I appreciate that Plesk is a balance between an easy interface for non-technical people and also used for the technical parts - there are a number of areas (including this) where it would be good to have basic options immediately visible, and an expand to show the more complicated settings with explanations. We also had problems when updating MailEnable because we couldn't do this through the Plesk interface

+1

+1

This has been on here since 2014. By the time this gets implemented traditional email may be obsolete.