Kontact Touch with separate IMAP server for outgoing mail?

[Oliver Sander]

Dear PA team,
[apologies if I am posting to the wrong list]
I have installed PA (with the open-slx 126 image) on my old WeTab 3G.
While many things work very nicely, I have encountered the following
problem:  I tried to set up the mail client to communicate with a t-mobile
imap account.  The automatic setup found the account directly, and
reading emails was very easy.  However I have not been able to send
emails.  Upon trying I get a little notification widget saying 'mail could
not be added to the waiting queue' (or something like that -- the actual
text is German).
I suspect that the reason may be that t-mobile uses different imap-servers
for incoming and outgoing mail.  However in the Kontact Touch account
settings I see only one server.  Is there a way to configure the program
to send mail via a separate second server?  With the gui or by editing
some config file?  Your help is much appreciated.
cheers,
Oliver