Issue with scanning on Xerox WCP 275

I am having an odd issue with one of my users at work. we have a Xerox Workcenter Pro 275. We have email and network scanning enabled. I have also setup LDAP on it using our internal address book. So when most of my users scan to their email account (Outlook) they receive the file. They either type in their email address or use LDAP. But when one of my users scans to her email, it does not show up. There is no error message from the Xerox. It only prints when it cannot scan to email. It is not in Junk Mail or anywhere else in her email. this only happens randomly. so not all the time. most of the time its just a word document, only one page, probably less than 1 MB. the problem is why does this happen randomly when noone else is having this issue. has anyone else seen something so random as this. is this an AD issue?