So finally it works. ShovelhEd from HowardsForum wrote the orignal guide to the K750i, but it kinda works on k800i with some tweeking.

First off, open up your e-mail settings are create a new account. Now follow the instructions.

Account name: whatever (does not matter)
Connect with: GPRS Account (Not WAP)
Email adres: whatever@gmail.com
Protocol: POP3
Incoming Server: pop.gmail.com
User name: whatever@gmail.com
Password: .....
Outgoing Server: smtp.gmail.com

Now, move on to the "Advanced" settings

Encryption: Incomming should be "SSL" and Outgoing shoud be "TLs"
Outgoing username: whatever@gmail.com
Outgoing password: whatever
Incoming Port: 995
Outgoing Port: 465 OR 25

Now, we are not done yet here. Plugin your phone and choose "Phone mode".
Then download this file

http://www.q300.se/Equifax_Secure_Ce..._Authority.cer

Now, when the file is downloaded. Its time to install it!. Drag the file oever the icon in the Sony Ericsson File Manager folder that should be located on your desktop!.

Now, look at your phones screen. The phone should be asking you if you want to install an new certificate. Choose "Yes".

Now we are done. To test if it works, Try to send an e-mail and send an to ur g-mail adres. You might have to enable pop3 in ur g-mail account settings via the gmail.com site.

Hope this helped someone