E-mail attch problems

I have no idea what could be causing this. Every time Jane tries to send an attch to John, it does not send, and it does not send her a error message back saying it wasn?t delivered. I researched yesterday, but could not find any solutions. Jane said that her IT staff, not my company, told her that the file was no larger than 6k. I can only assume that the file is compressed, since the pdf is around 50-100 pages, but even if it is it is still not being sent to John. However Jane can e-mail both John and I without an attch, and we are on the same domain. Any help would be appreciated.

Thank you,