The following error appears when saving a ticket in Web Help Desk:
550 5.7.1 Client does not have permissions to send as this sender
All WHD versions
The user account in Microsoft® Exchange Server® 2007 or 2010 does not have the correct permissions to send an email.
Grant the Send As permission in Microsoft Exchange Server 2007 or 2010 to the user account or mailbox used to set up the outgoing mail account.
See the following Microsoft KB articles for more information: