Using regular expressions for email filtering

See also:
Filtering incoming emails
Combining multiple filters to build complex filter rules

Email filters also accept regular expressions for evaluating if the email passes the filter or not. For enabling this there is a check box down below the filter settings:

Once applied, Email Parser will run the regular expression using the text in the email as input. If there is a match the condition is considered to be met: Regular expressions are a topic on their own and, although very powerful, are complex as well. There are many tools online that can help you understand how they work:

• Regex one – Learn Regular Expressions
• Regex101, an online regex tester and builder