I doubt that this is a problem, since I've also tested this problem accessing two Exchange accounts located on the local server and had the same problem. The other Exchange account is located on another server which I don't have control over. One of the Exchange accounts uses a local server (running Small Business Server 2008 w/Exchange Server 2007). I don't remember what (if anything) I did to resolve the problem before. I've had this issue before with Outlook 2010, but then it went away and I was able to use both accounts without any problems. However, (usually) if I close Outlook and re-launch it, the account will send the message(s) in the Outbox, and I'll be able to continue sending email using this account - but if I try to then send an email using the account, it won't send. However, if I try to send a new message (or reply to a message) using the message will not be sent. If I open Outlook and compose a new email using that message will be sent - and I can continue to send email through this account. It seems that, upon opening the program, whichever email account sends the first outgoing message is the one that will actually send email - the other email account just retains the message in the Outbox. When attempting to send email from the second account, the email just remains in the Outbox and won't send. I am able to recieve email from both Exchange accounts, but I'm only able to send email using one of them. I am having an issue using two MS Exchange email accounts (each one on a different server) within Microsoft Outlook 2010.

Two email accounts in outlook 2010