It is not possible to connect to port 587 on Plesk Windows server with MailEnable
Connecting to port 587 on the server with telnet is not possible:
# telnet 192.0.2.2 587
telnet: connect to address 192.0.2.2: Connection refused
Port 587 appears filtered when trying to connect from outside:
# nmap -p587 192.0.2.2
PORT STATE SERVICE
587/tcp filtered submission
Nmap done: 1 IP address (1 host up) scanned in 0.59 seconds
MailEnable is configured as described in this article:
Port 587 is filtered in a firewall or by Internet Service Provider.
Make sure that inbound connection to port 587 is allowed in Plesk Firewall as explained in The Plesk Firewall ( Windows): Viewing and Managing Allowed Inbound Connections:
- Log into Plesk
- Go to Tools & Settings > Firewall > Firewall Rules > Add Firewall Rule
- Specify the firewall rule for port 587 and apply the changes
Note: In case Internet Service Provider blocked the port, contact their support in order to open it from their side.