Messaging works on store and forward mechanism, there is no way admin can automatically resend/retry to send the failed messages. A DLR to this effect is issued immediately. However admin can configure a fail-over gateway to handle such failure.

It may be noted that billing is already done for such message, hence fail-over gateway cost should be taken in consideration. Over and above stop loss feature will also apply.

However, the user can resend campaigns which are already been executed in past. Any past campaign which is still in pipeline of the queue or long messages will not be eligible for the resend feature.