mxORB

[faq] How do I blacklist an email address domain?

Using regular expressions it is possible to blacklist all emails from a specific domain. In the examples below, the domain we want to block is spammerdomain.com. Follow the steps below to add a blacklist filter:

• Open the mxORB configuration tool
• On the settings tab, double click on the Blacklist icon
• On the Sender Email Address tab click Add
• In the email address textbox enter ^\S+@spammerdomain\.com$
• Enter a description of the email address filter and ensure the Regular Expression option is checked
• Click OK add the filter and then click OK to save the changes to the Blacklist

The regular expression ^\S+@spammerdomain\.com$ can be broken down as follows:

• The ^ means match the start of the email address
• The \S+ means match one or more non-whitespace characters
• The @ means match the @ sign
• The hotmail\.com matches hotmail.com (note the backslash in front of the period - this is necessary because the period has a special meaning in regular expressions)
• The $ matches the end of the email address. This means the only emails ending @hotmail.com will match, @hotmail.com.uk, @hotmail.com.br, etc. would not match

If you want to filter a domain and any possible subdomains (for example: user@spammerdomain.com, user@sub1.spammerdomain.com, user@sub2.spammerdomain.com, etc) you can use the following: ^\S+@(?:\S+\.)*domain\.com$

• The ^ means match the start of the email address
• The \S+ means match one or more non-whitespace characters
• The @ means match the @ sign
• The (?:\S+\.) means match one or more non-whitespace characters followed by a period
• The * matches the expression in brackets zero or more times, this means that an address will match if it contains zero, one or more subdomains
• The domain\.com matches the required domain and you would change this as appropriate
• The $ matches the end of the email address

Date: July 29th 2004