Missing emails after migration

Hello,

I have 1 user missing most of her email after I migrated her mailbox from server 2007 to server 2013. I check the exchange log file I see it delay.

Delivery Report for  username ‎(username@mydomain.com)‎

Submitted
7/22/2013 1:16 PM GMS-S12EX2K13
The message was submitted to gms-s12ex2k13.gmsinc.local.

Pending
7/25/2013 4:46 PM GMS-S12EX2K13
Message delivery is taking longer than expected. There may be system delays. For more information, contact your helpdesk.

can someone help?

Thanks

Jimmy