Share your experience!
I succeeded to read my mails via POP3 port 110, no problems.
But I can't send any mail through SMTP port 25?
I use the same settings as on my computer but the phone always give me an error.
It's SMTP + server address + no verification.
Try using port 2525, 587 and 465, and see if any of these work. Otherwise, try changing the Encryption setting between SSL,TLS and No encryption and/or the SMTP Authentication setting.
Is this a Hotmail account?
Port 25 works fine for my computer, port 587 also does it well. But not with the phone...
It is not gmail/hotmail, just a regular mail account from my provider.
If you let me know which provider it is, I might be able to help you.
It's Telenet (Mechelen, Belgium) : the smtp server address is uit.telenet.be.
Both ports 25 and 587 seem to be open (I can use them with my computer but not with the phone)...
Have you tried changing the Encryption and SMTP Authentication settings in your phone?
I tried all possible combinations, very strange.
So incoming mail: no problem but outgoing won't work!
My computer is connected via utp ethernet to my (simplistic) router.
I also tried to disable the lan and enable the wireless mode : sending mail works fine through
port 25 with that server, so it's not the wireless part.
But not with the phone 
You may need to set up your outgoing server according to your mobile provider's SMTP settings, rather than your email provider's settings--this is sometimes necessary with email clients.
That's not really logical. So I can read mails through wifi but not send ??? I don't use any mobile connexion it's too expensive here in Belgium.
Yes you're right, it doesn't make sense over wifi, so I can only suggest you contact your email provider and ask them for the correct SMTP settings.