My boss sent out an email from my Exchange 2010 org and attached a PDF and a Word doc to it. He came back the next day and told me that some of the 8 or 10 people that received this email could open up the attachments no problem. The other 2 or 3 people, could not.

One of these people who could not open the attachment, went so far as to call Comcast (his email service provider) and ask them where his attachments went. Comcast told this person that when they received the email, the attachment was 0 bytes in size.

This may sound like more of a rant than a question but I'm genuinely concerned. Is there any possible way that something could have gone wrong on my end that sent out the email to some with the attachment and to some without?