Flag users for re-verification after [xx] hours
This option helps maintain the user list by periodically asking the verification source if users still exist. After the designated number of hours, verified users are flagged to be re-verified the next time they send or receive email. Disabled users are not deleted.
Cache negative responses for [xx] minutes
When a query to a verification source shows that an account doesn't exist, this option will cache the result for the designated number of minutes. This helps limit the number of redundant queries made to the verification source.
Always query default user verification sources for external aliases
When enabled, all unknown addresses will be validated by querying the default user verification source(s). If the user verification source returns that the address is an external alias for a user of a local domain, the local user will be created if necessary and the alias associated with the user. The use of this feature requires at least one default user verification source to be defined.
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Since all unknown addresses will be queried, a large number of queries may be made. |
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