Optional list of domains whose subdomain structure will be stripped off in email addresses.
The list is processed left to right, and processing stops at the first match. Thus,
masquerade_domains = foo.example.com example.com
strips "user@any.thing.foo.example.com" to "user@foo.example.com", but strips "user@any.thing.else.example.com" to "user@example.com".
A domain name prefixed with ! means do not masquerade this domain or its subdomains. Thus,
masquerade_domains = !foo.example.com example.com
does not change "user@any.thing.foo.example.com" or "user@foo.example.com", but strips "user@any.thing.else.example.com" to "user@example.com".
Note: with Postfix version 2.2, message header address masquerading happens only when message header address rewriting is enabled:
The message is received with the Postfix sendmail(1) command,
The message is received from a network client that matches $local_header_rewrite_clients,
The message is received from the network, and the remote_header_rewrite_domain parameter specifies a non-empty value.
To get the behavior before Postfix version 2.2, specify "local_header_rewrite_clients = static:all".
Example:
masquerade_domains = $mydomain[/code]