- Plesk for Linux
Unable to receive/send e-mails.
Emails cannot be sent by using PHP script.
It is not possible to connect to the server by telnet on port 25:
# telnet 192.0.2.2 25
telnet: connect to address 192.0.2.2: Connection refused
Port 25 appears filtered when trying to connect from outside:
# nmap -p 25 example.com
PORT STATE SERVICE
25/tcp filtered smtp
Outgoing mail connections via 25 port are not possible:
# telnet mail.example2.com 25
telnet: connect to address 203.0.113.2: Connection timed out
Trying 2001:db8:f61:a1ff:0:0:0:80... telnet: connect to address 2001:db8:f61:a1ff:0:0:0:80 Network is unreachable.
It is possible to send out an email message locally using the command:
# telnet localhost 25
SMTP Port 25 is blocked by a firewall.
- If the Plesk Firewall is used, open mail port under Plesk > Tools & Settings > Firewall;
- If the system or a third party firewall is active on the server, make sure that it is not blocking the connection to the 25 port.
- In case of an intermediate firewall, it is required to contact the service provider.
- For AWS instance, open port 25 according to Amazon documentation.
- For Azure instance, open port 25 according to Azure documentation.