Windows 10: Mail Client with Downloaded Messages and Password Encryption

I'm looking for a mail client that encrypts not only my mail ids and passwords but also downloaded messages. Possibly with mail-to-mail end encryption. It would be even better if the application was open-source. Is there anything like that or is it too much for my expectations?

I know that thunderbird encrypts my passwords and its enigmail plugin enables pgp usage but it doesn't encrypt downloaded data so even when the attacker doesn't know my gmails data, he/she can still access all the storage that was downloaded from the server previously.

:)

 

Standard E-Mail client and security

Currently I use the standard e-mail client that came with the N82 to handle e-mail.



I connect to Wifi at home and to GPRS on the road.



I use e.g. a Yahoo mail account. Yahoo SMTP/POP3 does not support any encryption. So I wonder, when I check my mail, will the passwords be blown plain text into the air?

 

Installation and setup on N97

I went to email.nokia.com and signed up for nokia messaging.

I then went to email.nokia.com from my n97 and downloaded the messaging client and installed it as requested.

I went into applications and started the "E-mail setup" program and it asks for an email address and password.

I give the client my email address and password, and it says, mailbox set up in messaging folder.

Now I just see the mailbox in my old messaging client. If I open the email program with the red @ symbol for an icon, it just takes me into an email setup dialogue again.



grrr...how do I install the updated messaging client?



Thanks.