Mail app not seeing outgoing mail server : it's there in the account info!?

Question

I just set up 2 new accounts in mail all setting are ok and email is being received OK by both accounts.
Accounts are named John@blah and enquiries@same blah
But one of them (john) is not sending and I'm getting this:
[IMG]http://i13.tinypic.com/2z6fmvm.png[/IMG]
Where I'm told to choose a different outgoignmail server. Problem is that in accounts setting the server is named correctly but this drop doen panel doesn't give me the option to use it.
I need some help please

Answer 1

I know that's what you'd think but it is not the case as it's already there, look:
[img]http://xs414.xs.to/xs414/07165/Picture.png.xs.jpg[/img]
Could it be the server port. the 2 accounts that send ok use 25 and the one that isn't working, ie the one where I am unable to select the correctct outgoing server uses port 587.
I have no idea if this would effect mailapps ability to read what is in mail>preference>accounts I can't see how that would be a problem
  Mac OS X (10.4.9)   iMac C2D 20" 2.16 2GB RAM & PB 1.5GHz 1GB RAM
  Mac OS X (10.4.9)   iMac C2D 20" 2.16 2GB RAM & PB 1.5GHz 1GB RAM