// REFERENCE
Port 25 (SMTP)
Protocol: TCP
Service: SMTP
Medium risk
SMTP: mail delivery between servers (MTA to MTA). Clients submit mail on 587 instead. A misconfigured open 25 can become a spam open relay.
Related tools
Work with this in:
Related
110
Port 110 (POP3) 143
Port 143 (IMAP) 465
Port 465 (SMTPS) 587
Port 587 (SMTP submission) 993
Port 993 (IMAPS) 995
Port 995 (POP3S)
Port 110 (POP3) 143
Port 143 (IMAP) 465
Port 465 (SMTPS) 587
Port 587 (SMTP submission) 993
Port 993 (IMAPS) 995
Port 995 (POP3S)
Assignments per the IANA port registry. Educational content.