This module checks the Subject header of a message and ensures that it starts (modulo an initial Re:) with a valid keyword. By default, the following keyword formats are supported:
KEYWORD: KEYWORD/KEYWORD: [KEYWORD] [KEYWORD/KEYWORD] [KEYWORD][KEYWORD]
If multiple keywords are given, they all have to be valid. Keywords are checked against a list given in a file and are case-insensitive.
This module takes one optional argument, a reference to a sub which, if given a subject line, returns a list of all the keywords present. This can be used to override the default patterns listed above.
There is one required configuration file directive:
- keywords FILENAME
Specifies the file from which the list of valid keywords will be read. The file should list all valid keywords, one per line.
Two failure messages are possible:
- No keywords found
There were no keywords in the subject header of the message.
- Invalid keyword '%s'
A keyword was found that wasn't in the list of valid keywords.