Error (MTA): unreasonable virtual alias maps map expansion size
A message sent to a large distribution list can cause an MTA error if the number of members on the list exceeds the maximum addresses allowed for alias expansion. The default is 1000 addresses.
Jul 31 16:14:35 server postfix/cleanup: warning: 06EFD283A887: unreasonable virtual_alias_maps map expansion size for email@example.com
As a result, user or administrator defined forwarding email addresses will not receive messages sent to the distribution list since alias expansion (virtual alias mapping) cannot be completed.
The message will not be received by any forwarding address configured by the user or administrator. If "Disable local delivery" is checked under account preferences (zimbraPrefMailLocalDeliveryDisabled=TRUE), then the mail will not be received by the member of the list.
Increase the virtual_alias_expansion_limit Postfix parameter to the value of the highest number of distribution list members. All commands run as the zimbra user.
$ postconf virual_alias_expansion_limit
$ postconf -e virtual_alias_expansion_limit=3000
$ postfix stop $ postfix start
Keywords: mta, postfix, postconf, bug, distribution list, virtual, alias, forward