Mailparser offers the option of using regular expressions (or regex) to search and replace or isolate specific patterns of data. This option is available for both the text and table versions of "Search & Replace Text".
via Text filters
via Table filters
Mailparser utilizes the PCRE version of regex and does require that all expressions open and close with a forward slash "/".
Some basic examples are shown below which should get you started. For more in-depth information, please have a look at the PCRE syntax documentation.
Example #1: Find all integer numbers which are between seven and nine digits long
/[0-9]{7,9}/
Example #2: Find all text tokens which consist of two letters followed by a dash symbol and seven digits:
/[A-Z]{2}-[0-9]{7}/
Next to writing down the actual pattern, a delimiter character needs to be placed at the start and the end of the expression. Common delimiter characters are / or #.
Instead of defining the character sets like shown in the example above, one can also use specific letters representing character classes (for example, \d is the same as [0-9]). Below we will list the most common PCRE syntax elements.
Base Character Classes
| \w | Any “word” character (a-z 0-9 _) |
| \W | Any non “word” character |
| \s | Whitespace (space, tab CRLF) |
| \S | Any non-whitepsace character |
| \d | Digits (0-9) |
| \D | Any non-digit character |
| . | (Period) – Any character except newline |
Meta Characters
| ^ | Start of subject (or line in multiline mode) |
| $ | End of subject (or line in multiline mode) |
| [ | Start character class definition |
| ] | End character class definition |
| | | Alternates, eg (a|b) matches a or b |
| ( | Start subpattern |
| ) | End subpattern |
| \ | Escape character |
Quantifiers
| n* | Zero or more of n |
| n+ | One or more of n |
| n? | Zero or one occurrences of n |
| {n} | n occurrences exactly |
| {n,} | At least n occurrences |
| {,m} | At most m occurrences |
| {n,m} | Between n and m occurrences (inclusive) |
A great online resource for creating and testing Regular Expressions is https://regex101.com/. Here you can insert your strings and test the expression to ensure it is correct and working.
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