228 Fortinet Inc.
Blocking oversized files and emails Antivirus protection
3Type the new pattern in the File Pattern field.
You can use an asterisk (*) to represent any characters and a question mark (?) to
represent any single character. For example, *.dot blocks Microsoft Word template
files and *.do? blocks both Microsoft Word template files and document files.
4Select the check box beside the traffic protocols for which you want to enable blocking
of this file pattern.
5Select OK.
Blocking oversized files and emails
You can configure the FortiGate unit to buffer 1 to 15 percent of available memory to
store oversized files and email. The FortiGate unit then blocks a file or email that
exceeds this limit instead of bypassing antivirus scanning and sending the file or email
directly to the server or receiver. The FortiGate unit sends a replacement message for
an oversized file or email attachment to the HTTP or email proxy client.

Configuring limits for oversized files and email

To configure limits for oversized files and email
1Go to Anti-Virus > Config > Config.
2Type the size limit, in MB.
3Select Apply.
Exempting fragmented email from blocking
A fragmented email is a large email message that has been split into smaller
messages that are sent individually and recombined when they are received. By
default, when antivirus protection is enabled, the FortiGate unit blocks fragmented
emails and replaces them with an email block message that is forwarded to the
receiver. It is recommended that you disable the fragmenting of email messages in the
client email software.
To exempt fragmented emails from automatic antivirus blocking
1Enable Pass Fragmented Emails for IMAP, POP3, and SMTP traffic in a content
profile.
2Select Anti-Virus & Web filter in a firewall policy. For example, to pass fragmented
emails that internal users send to the external network, select an internal to external
policy.
3Select a content profile that has Pass Fragmented Emails enabled for the traffic that
you want the FortiGate unit to scan.
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Caution: The FortiGate unit cannot scan fragmented emails for viruses or use file pattern
blocking to remove files from these email messages.