How to Secure Email Using SSL and PGP
If you have the Public key of the receiver of your email you can encrypt the emails for him and by default the PGP Desktop will work for you without any changes to the email client you use. Ports used by PGP are 25 for SMTP and port 110 for POP emails sent through the SMTP-25 port are encrypted by PGP if the recipient’s public key is found; if not found then the email is sent in clear text as the rule suggest. If your email client use different port number other than SMTP – 25 then the emails are not encrypted by PGP as it tracks the port 25. Even if the emails are encrypted by the SSL certificates by email client and then passed to PGP still it does not recognize the message and encrypts it again. Solution here is to configure the email client for sending emails through port25 and here the PGP desktop will communicate to SMTP server through SSL/TSL secure tunnel.
PGP Desktop on windows OS
PGP email encryption enabled