Practice point: An affidavit of service is prima facie evidence that the defendant was properly served with the summons and complaint, pursuant to CPLR 308(2). In order to rebut the prima facie showing, the defendant must submit a sworn, nonconclusory denial of service, or swear to specific facts to rebut the statements in the process server's affidavit.
Student note: A defendant's mere assertion that he was never served is insufficient to rebut the presumption of proper service.
JP Morgan Chase Bank v. Dennis, NY Slip Op 08070 (1st Dep't November 27, 2018)
Here is the decision.