HTC Inspire vs. msn.com email

Newbie on this forum and just got an HTC Inspire.  Very nice device!  I have a problem with sending email from my msn.com email account.  I cannot send email in wi-fi mode, must disable this and connect to the network via my data plan connection.  No problem receiving my msn.com email on either mode, just cannot send via wi-fi.  Tech support forum says to disable wi-fi if problems occur sending/receiving email but I wanted to check to see if others have had this problem and if it is simply a different setting on my cell phone.  Would really like to be able to send email via wi-fi to reduce my data usage if possible.  TIA!