Bought my N9 week ago and very interesting thing i noticed. 
My software version is PR1.3
I can receive mail with no problem, but every time the phone sincs the mailbox, it also sends mail.
Now, if i put my outgoing mail server to be the one from the network provider, in my case VIP (Croatia) it is
mail.vip.hr
When I am home, my wifi network kicks in, which is from a different provider (T-Com) and their outgoing mail server is
mail.t-com.hr
So all the time I am home, whenewer mail sinc is due, i get "can't connect to server error", I still get my mails, since it is the same incoming mail server.
Even though i do not have any mails to send, i get this error, and also because of outgoing mail server difference, I can not send mails through my wifi.
Only workaround that I see is to turn of wifi, and leave it to use 3,5G from my network provider.
Now i also remembered:
On my old C6-00, in mailbox settings, there was dedicated option of which connection to use for the outgoing and again for incomming messages, so i had my network provider set for incomming, and for outgoing mails this was set to "always ask", so I could choose when needed.
This solves the problem astually.
Is it possible upgrade the mailbox accordingly? pretty please 
