The tax version of the mailbox rule occasinally rears its head in cases (e.g., Trout v. Commissioner, 131 T.C. No. 16 (Dec. 16, 2008)) and articles (e.g.,Burgess J.W. Raby & William L. Raby, Abolishing the Mailbox Rule for Tax Documents, 105 Tax Notes 193 (Oct. 11, 2004).  One of the traumatic experiences of my youth was when the Red Sox mailed Carlton Fisk a new contract one day late, he became a free agent under the terms of the collective bargaining agreement and eventually signed with the Chicago White Sox.  From the what goes around comes around file:  press reports out of Chicago indicate that the Black Hawks may have similarly screwed up hockey's version of the Mailbox Rule with a number of its star players:

The Blackhawks had until June 29 to qualify the Hawks' restricted free agents, which would give the team the right to match any offers the players might receive from around the league. The common procedure is to send the offers to the players and their agents via courier and fax and also to fax a copy to the league. At least one player, Johnson, still had not received his offer Saturday …

The CBA stipulates that qualifying offers must be sent via an established overnight delivery service, or certified or registered mail if overnight service is not available, to the players and their agents.

(Hat Tip: Mike Kirsch.)