What is SMTP and which are the default SMTP ports

Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending emails across the Internet.

     By default, the SMTP protocol works on three ports:

• Port 25 - this is the default SMTP non-encrypted port
• Port 2525 - this port is opened on all SiteGround servers in case port 25 is filtered (by your ISP for example) and you want to send non-encrypted emails with SMTP
• Port 465 - this is the port used if you want to send messages using SMTP securely