[Evolution] SMTP Question

[Steve T <stevetucknott yahoo co uk>]

Using Evolution 3.2.3 under FC16

I have Evolution working with multiple external POP/SMTP accounts for quite a while (years) and have a basic couple of questions on SMTP.

For a couple of accounts that I have (paid EMail accounts) it seems that I need to pay for SMTP Authentication to send mails from a client. The first question is:
Do I need multiple SMTP connections? IE Can I send a mail message from say blah somemail com via an SMTP connection at smtp.blah.blah. Can I just use one smtp account to send all my mail, even though the 'From' is not part of that 'email domain'?
 
Secondly, I tried to change one of my accounts to test the above and altered the sending options from smtp.blah.blah to smtp.x.y and then created a mail from that account. When I troed to send the mail, it said something  like  smtp.blah.blah could not accept the connect. IE quoting the OLD smtp mail server. I thought that it may be using the smtp connection from the default account, so disabled all the 'other' accounts and made the default account the 'from' account. Still the same message. So I restarted Evo and tried again - still the same, although the account being used has no reference to smtp.blah.blah. Where is this smtp server detail coming from? Is there another config file I need to change?