Defaultdomain Option

From MsgServerDocWiki

When POP, IMAP and SMTP users authenticate, they typically provide an unqualified user ID (a user ID without a domain portion). The value of the defaultdomain option is appended to unqualified user IDs. When used as an MMP virtual domain option, this allows a single MMP server with multiple IP addresses to support unqualified user IDs for multiple hosted domains. This may also be set as a service-wide option.

Use with base

Messaging Server default domain. This is used to determine whether a domain is the default domain or a hosted domain.

The default value in this context is the empty string.