Security issue reading xml file sent as attachment

In my project I receive Emails with xml attachments,  I read these attachments and insert relevant information into the DB.

(myxmldocument.SelectSingleNode("/info").InnerText

Which security precautions have to be taken care of - when reading the attaachments. 

I do only read the xml attachments received from a specific address- but this can also be forged, no?