Ala. Code § 15-13-135

If the notice is not served on any of the parties to the undertaking, such other notices as are necessary, may, from time to time be issued, but two returns of “not found” by the proper officer are equivalent to personal service, unless one of the parties shows evidence that such “not found” service was not diligently executed by the officer or the officer did not attempt to serve the proper party as prescribed by law. If service was by certified mail and is returned without a signature of acceptance, then the clerk shall reissue it to be served by an officer as specified in Section 15-13-134 and a return of the service “not found” by the proper officer is equivalent to personal service.