The evidentiary presumption under federal common law that a letter that was properly addressed and mailed will be received by its intended recipient, also known as the “mailbox rule,” dates back to the U.S. Supreme Court's 1884 decision in Rosenthal v. Walker. 111 U.S. 185, 193 (1884). In Rosenthal, the court held that the presumption is “a mere inference of fact, founded on the probability that the officers of the government will do their duty and the usual course of business” in delivering the mail to its intended recipient. Id. at 193. The presumption is rebuttable, however: If the intended recipient contends that he never received the letter, then the factfinder must decide the resulting issue of fact.

The mailbox rule often arises where notice is a determinative issue. For example, under the Family and Medical Leave Act (FMLA), an employer is required to notify a covered employee if a leave of absence falls under FMLA. 29 C.F.R. §825.300. In related litigation, the employer can prove mailing and invoke the mailbox rule to establish that the employee received the notice. See, e.g., Lupyan v. Corinthian Colleges, 761 F.3d 314 (3d Cir. 2014). Similarly, under the Employee Retirement Income Security Act (ERISA), an employee may be required to file documents in a timely manner to receive plan benefits. Where the plan administrator denies receipt of the requisite documents, the mailbox presumption may come into play upon proof of mailing. See Schikore v. BankAmerica Supplemental Ret. Plan, 269 F.3d 956 (9th Cir. 2001).

Email Does Not Ensure Delivery

Email may seem inherently more reliable than “snail mail” given that electronic transmission is facilitated entirely by computers and eliminates the mail carrier and other humans capable of errors and omissions. However, several issues unique to email can prevent messages from being sent or received. For example, an email may fail to transmit when an attachment contains too much data. Similarly, an email may never be received, as a practical matter, if the recipient's “spam filter” catches the email, or if the recipient intentionally blocks or filters emails from a specific email address or domain. Even more unpredictably, server, network, and local computer problems may interfere with the receipt of emails.