mailabbrevmailabbrev is Emacs’s “abbrev-expansion of mail aliases”, and
it is part of Emacs. It stores all information in a mailrc
file, whose location, and name can be configured via the variable
mail-personal-alias-file (which see). The mailrc file
has the same format as the mail and mailx commands
use for their startup configuration file. mailabbrev processes
‘alias’, and ‘source’ statements in the mailrc file.
‘alias’ statements can define simple aliases and distribution
lists, and can be nested in that the alias expansion can contain
references to other alias definitions. Forward references, that is
references to aliases before they are actually defined, are possible,
too.
Originally, mailabbrev was designed to be used with
abbrev-mode. The mailabbrev EUDC backend does not use
abbrev-mode, but queries mailabbrev for alias entries
only, and returns these as EUDC results. All entries where the alias
name exactly equals either the email, name, or
firstname attribute value in the EUDC query, will be returned
as matches. When a mailrc alias defines a distribution list,
that is it expands to more than one email address, the EUDC result
will contain a single entry, which will contain an email attribute
only, whose value will be a comma-separated list of RFC 5322 formatted
recipient specifications.