Once a new address is added to a constituent's record, it is useful to know when addresses were changed or added, thus using the 'valid to' or 'valid from' field next to an address is useful. This is not a seasonal address situation, the seasonal address field option is not checked. Subsequently, if the new address becomes obsolete, without a new updated address, the record should be marked 'Do Not Mail', ie. if mail to that new address is returned. However, at this point, using the Do Not Mail option incurs an error message saying 'One of the addresses is invalid because it has a seasonal start or end date but it is not marked as seasonal.' Thus I have to remove the 'valid to' or 'from' information in order to mark as Do Not Mail, losing historical data.