I have 2 users that will occasionally not be able to forward emails, when they click Send nothing happens.
This only happens when forwarding an email with an attachment, but not every time, 1 of the users having this issue forwards about 20 emails a day w/ attachments, but has the issue with one or two emails a week.
The recipient's email address is correct, starting a new email with all the same details will send.
While the email that won't send is still open I can successfully send other emails to other recipients.
In the application event log on the desktop
Event ID 27
"The operation failed"
I see nothing wrong on the Exchange server.
Outlook 2010 - cached mode enabled Windows 7 x86
Everything is fully patched.