TCP
SMTP
What port 25 is used for
Primary SMTP port for server-to-server mail delivery.
Security considerations
Open relays get abused by spammers — configure SPF/DKIM/DMARC.
Check if port 25 is open on any host:
Open Port Scanner →Primary SMTP port for server-to-server mail delivery.
Open relays get abused by spammers — configure SPF/DKIM/DMARC.
Check if port 25 is open on any host:
Open Port Scanner →