Enigmail Help
Using the Enigmail Rules Editor
In the Rules Editor, you can specify defaults per recipient for enabling 
encryption, signing and PGP/MIME, and to
define what OpenPGP key(s) to use. Each rule consists of 5 fields and is represented
on a single line:
  - Email: the e-mail(s) from
    the To:, Cc: and Bcc: fields to match. The matching works on substrings (Further details can be
    found in the Edit Rule dialog)
  
- OpenPGP Key(s): a list of OpenPGP
Key ID's to use for the recipient
- Sign: enable or disable
    message signing. This either uses or overrides what you have specified
    in the message composition window. The values are:
  
    - Never: disable signing, even if it was enabled in the message
       composition window (overrules the other values)
 
- Possible: leave signing as specified in the message composition
      window
- Always: enable signing, even if it was not enabled in the message
      composition window
    
These signing settings are applied for
all rules that match. If one of the rules disables signing, the message
will not be signed, regardless of other rules that specify Always.
  - Encrypt: enable or
    disable message encryption. The allowed settings and their meaning are
    the same as for message signing.
- PGP/MIME: enable or
    disable the use of the PGP/MIME (RFC 3156) message encoding. 
    If PGP/MIME is disabled, the
    messages are encoded using "inline PGP". The allowed values and their
    meaning are the same as for message signing.
  
The rules are processed in the order displayed in the list. Whenever a rule 
matches a recipient and contains a OpenPGP Key ID, in addition to using the 
specified Key ID, the recipient is not considered anymore when processing 
further rules.
Note: The rule editor is not yet complete. It is possible to write
some more advanced rules by directly editing the rules file (these rules
should then not be edited anymore in the rule editor). Further
information for directly editing the file
is available on the Enigmail Homepage
Further help is available on the
Enigmail Help web page