Of course brian is right ... you're going to have to work with the sendmail admin to ensure you have your local sendmail daemon configured correctly to support the queueing. Once that's done, you can use the -odd option to sendmail for the quickest async operation (all database lookups (DNS) are deferred until the queue is run). The downside to this approach is normally delayed delivery. It may take some time for the queue to be processed and hence your mail delivered.