- Plesk for Linux
- Unable to send or receive e-mails from remote mail addresses.
- Customer in Plesk is unable to access Plesk Email Security extension, the following error message is displayed:
PLESK_ERROR: Hostname is not valid. Please set a hierarchical, dot-separated domain as the hostname!
The following error messages can be found in /var/log/maillog:
CONFIG_TEXT: hostname postfix/smtpd: NOQUEUE: reject: RCPT from unknown[203.0.113.2]: 450 4.7.25 Client host rejected: cannot find your hostname, [203.0.113.2]; email@example.com firstname.lastname@example.org proto=ESMTP helo=<info.example.com>
The server hostname must be a fully qualified domain name (FQDN).
Go to Tools & Settings > Server Settings and set a Full hostname.
If hostname already set, change it to some random one (ex. test.example.com) and then change back to correct hostname.
Open Plesk Email Security in Extensions > My extensions > Plesk Email Security > Open
Click the button Install Now!