Attachment won't send

I was trying to send a 5Mb attachment, the operation tab indicated that it was sending until the message disappeared and the file was still in the outbox and clearly had not been sent.  
I had to use Outlook on another machine to send it…


What kind of protocol and e-mail service are you using?


The accounts was an MS 2010 Exchange server account, so whatever the standard support for that type of account was (is it via a webservice)?


In that case, you need to raise the limits for e-mail sizes in the server config itself.


You cannot set this yourself by settings available through the OWA interface and since this is a hosted service I have no access to server config.
Eventually I was forced to transfer the file to another machine where Outlook sent it through the same account without issue.