This issue occurs because of "begin 664." This indicates that UUEncoding is being used. When an email message contains an inline UUEncoded attachment, multipart MIME instead of MIME should be used. Otherwise, Microsoft Exchange translates the UUEncoded data as a part of the message body that has a MIME designator.
To resolve this issue, encode the message by using multipart MIME.
Note The issue cannot be resolved on an Exchange server because Exchange displays the messages according to the specified MIME encoding type.
For more information about MIME, visit the following website:
Microsoft Exchange Server 2010 Enterprise, Microsoft Exchange Server 2010 Standard, Microsoft Exchange Online, Microsoft Business Productivity Online Dedicated, Microsoft Business Productivity Online Suite Federal