Do mails in the outbox of a mailbox still get sent with Outlook closed?

Hi All,

Exchange version: Exchange 2007 SP3 RU5

I understand that the MSExchange Mail Submission service basically tells the HT servers to go through mailbox outboxes and submit any messages waiting to be sent. Normally this process is pretty seamless and the user would not realise it had even occured.

However, if a mailbox has several hundred messages waiting to go in the Outbox, and Outlook was closed, would it still process the mails via this method, or would Outlook need to be open for these to be sent?

It's strangely not something that has really come up for me before. From memory I think the mailbox does need to be opened in a MAPI client and the mails sent from that, but I could always be wrong.

Any insight appreciated.

Thanks,
Chris