mh-identity-handlers

mh-identity-handlers is a variable defined in `mh-e.el'.
Its value is

(("From" . mh-identity-handler-top)
 (":default" . mh-identity-handler-bottom)
 (":attribution-verb" . mh-identity-handler-attribution-verb)
 (":signature" . mh-identity-handler-signature)
 (":pgg-default-user-id" . mh-identity-handler-gpg-identity))

Documentation:
Handler functions for fields in `mh-identity-list'.

This option is used to change the way that fields, signatures,
and attributions in `mh-identity-list' are added. To customize
`mh-identity-handlers', replace the name of an existing handler
function associated with the field you want to change with the
name of a function you have written. You can also click on an
"INS" button and insert a field of your choice and the name of
the function you have written to handle it.

The "Field" field can be any field that you've used in your
`mh-identity-list'. The special fields ":attribution-verb",
":signature", or ":pgg-default-user-id" are used for the
`mh-identity-list' choices "Attribution Verb", "Signature", and
"GPG Key ID" respectively.

The handler associated with the ":default" field is used when no
other field matches.

The handler functions are passed two or three arguments: the
FIELD itself (for example, "From"), or one of the special
fields (for example, ":signature"), and the ACTION 'remove or
'add. If the action is 'add, an additional argument
containing the VALUE for the field is given.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 8.0 of the MH-E package that is part of Emacs 22.1.