Default port for SMTP, POP and IMAP:
- SMTP AUTH: Port 25 or 587
- SMTP StartTLS Port 587
- SMTP SSL Port 465
- POP Port 110
- POP SSL Port 995
- IMAP Port 143
- IMAP SSL Port 993
- IMAP StartTLS Port 143
Source: Uttam Kumar Roy (2015), Advanced Java programming, Oxford University Press.