Question
Is it possible to configure relayhost in Plesk with Postfix?
Answer
Currently, Plesk does not provide such functionality. Vote for implementation of possibility to configure relayhost for Postfix at Plesk UserVoice portal. Top-ranked suggestions are likely to be implemented in new product versions.
Alternatively, relayhost can be configured by modifying Postfix main configuration file located in /etc/postfix/main.cf, using instructions provided by Postfix official documentation.
Warning: Such customization has not been tested and is not officially supported by Plesk, so it should be performed at your own risk.
Note: Any customization made in Postfix configuration can be overwritten by Plesk Update (for example, in case of bug fix, when configuration files are updates), Plesk Upgrade or by mchk utility, which resets default mail server configuration.
As an option, mail can be sent via SendGrid.