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Updated:July 8, 2014
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If you want to block mail to a recipient and specify the recipient address with a wildcard, you must use a message or content filter. Filters allow you to use regular expressions to match the sender or recipient addresses.
The ESA uses Python regular expressions. A simple wildcard construct is ".*", which will match zero or more characters up to a new line. The "." matches any single character, and the "*" matches the previous expression zero or more times in a row. Let's say you want to match recipients helpmail1, helpmail2, helpmail3, @example.com. A filter expression to match these is
The ^ matches beginning of line and the $ matches end of line, which limits the match to only email@example.com, but will not match firstname.lastname@example.org, or email@example.com. "\\" is an escape before the ".", so it will be taken literally. You can then use this regular expression in a message filter:
DropHelpmail if (rcpt-to == "^helpmail.*@example\\.com$") drop(); }
You can also create this as a content filter, simply by choosing 'contains' and entering the regular expression into the condition window: