Alias-sensitive rewrites

Alias-sensitive rewrites, and
It is possible to have rewrite rules whose application is dependent upon whether or not the address being rewritten was the result of an alias. (Note that inherently, only envelope To addresses can possibly be the result of an alias.) This can be useful in the case, for instance, where certain rewrite rule(s) should be applied only before alias expansion has occurred, while other rewrite rule(s) should be applied only after alias expansion has occured.

Alias-sensitive rewrite checking is triggered by the presence of the   or   control sequence in the template part of a rule. The   control sequence means that the rewrite rule will match only if the address being rewritten is the result of an alias. (So note that such a rewrite rule also is implicitly a   rewrite rule---it can only ever match envelope To addresses.) The   control sequence means that the rewrite rule will match only if the address being rewritten is not the result of an alias.

See also:
 * Aliases
 * Address direction and location-specific rewrites
 * Rewrite rule template substitutions and control sequences