Can you block custom extension types, such as *.exe,*.bat
Yes. You can use either commas OR newlines; you may not want the spaces after the commas.
For example: *.exe,*.bat
The Online Help says:
Message Attachment Filename Match
The following table provides details about the options for Message Attachment Filename rules and exceptions:
File Name Specify
The filename to match using the DOS pattern matching language to represent patterns in the filename. Separate the patterns to match with commas or by placing them on separate lines.
Attachments is preselected. You cannot change this selection for Message Attachment Filename rules.
The following DOS pattern matching expressions are supported:
. The file name and extension separator
* Any number of characters (including none)
? Any single character
Any other characters you enter match exactly. For example, to match a Word filename that begins with ENG- followed by any eight characters, enter:
If you are not sure it is a Word document, enter:
If you are not sure how many characters follow ENG-, enter:
To match all filenames that begin with ENG- and all filenames that begin with ITA-, enter: