Editing Email attachment (section)

===Dangerous file types===
Email users are typically warned that unexpected email with attachments should always be considered suspicious and dangerous, particularly if not known to be sent by a trusted source. However, in practice this advice is not enough – "known trusted sources" were the senders of [[Computer program|executable programs]] creating mischief and mayhem as early as 1987 with the mainframe-based [[Christmas Tree EXEC]].

Since the [[ILOVEYOU]] and [[Anna Kournikova (computer virus)|Anna Kournikova]] [[Computer worm|worms]] of 2000 and 2001, email systems have increasingly added layers of protection to prevent potential [[malware]]. Now, many block certain types of attachments.<ref>[http://mail.google.com/support/bin/answer.py?hl=en&answer=6590 ''"Some file types are blocked"'', mail.google.com].</ref><ref>[http://support.microsoft.com/kb/829982 ''"You may receive an "Outlook blocked access to the following potentially unsafe attachments" message in Outlook"'', microsoft.com].</ref>