Not getting friend's e-mails

I spoke with a friend by phone yesterday.  He said he's sent me several e-mails recently, but I never received them.  He had attachments on them of material that might be considered adult, and is worried some sort of block might've kept me from getting. them.  I don't know about that, but I'd like to know what is keeping me from getting them, and how can I get around it.  His e-mail is through