Using wildcards and regular expressions
You can enter wildcards or regular expressions in any pattern field, such as Reverse DNS pattern, on the Access Control Rule dialog.
To use a regular expression as a pattern, first select the Regular expression check box beside the pattern field.
If a pattern is listed on the Receiving tab with the R/ prefix, it is set to use regular expression syntax. If the pattern is listed with a -/ prefix, it does not use regular expression syntax.
Wildcard characters (* and ?) allow you to enter partial patterns that can match multiple reverse DNS lookup results. An asterisk (*) represents one or more characters. A question mark (?) represents any single character.
When configuring access control rules, do not leave any pattern fields blank. Instead, to have the FortiMail unit ignore a pattern:
• If Regular expression is disabled for the field, enter an asterisk (*) in the pattern field.
• If Regular expression is enabled for the field, enter a dot-star (.*) character sequence in the pattern field.
For example, if you enter an asterisk (*) in the Recipient Pattern field and do not enable Regular expression, the asterisk matches all recipient addresses, and therefore will not exclude any SMTP sessions from matching the access control rule.