Hi There, i have been experiencing the same issue, one of the guys i support called and advised they could not open a 55mb PDF attachment. these iPads are setup to recieve push mail from the coporate 2003 exchange server. our internal limit is 100mb and this PDf was sent internal. i got the message and attachment forwarded to my corporate mail account and started mucking around. i have downloaded PDFreader pro, goodreader, and PDF comrade, still no luck and receiving the attachment too large message. i then tried downloading the attachment from my mailbox via Outlook web access using safari, no good, timeout errors. i then forwarded to my gmail account, but then noticed the icon for the PDF attachment had changed in the mail app and now resembles the PDFreader pro icon. i can now open the 55mb attachment in the mail app, and get the option to "open in" in the top right. hope this helps guys 🙂