OtherInBox CEO Joshua Baer wants e-mail messages to carry with them the dates of their own deaths.

MOUNTAIN VIEW, Calif.--Joshua Baer, CEO of the e-mail company OtherInBox, agitated for a new addition to e-mail standards at the Inbox Love e-mail conference today. He's proposing a standard that would let e-mail messages carry with them the date of their own irrelevance.

E-mails could use the the "x-expires" header to tell the receiving in-box that they become outdated after a certain absolute date, or a certain time relative to when they're sent or received. Baer says this idea has been "bouncing around" for 10 years, but he's learned, "the best way to get a standard adopted is to work with individual companies first, and make it a de facto standard." That's what he's trying to do here.

This concept could help keep users' e-mail boxes cleaner and more relevant. Offers for discounts on Valentines' Day flowers could automatically vanish on February 15. Companies that blast out time-limited coupons (Groupon, LivingSocial) could serve users better by removing expired offers from in-boxes.

Other messages that become unnecessary after a period of time, such as notifications of activity in groups, shipping notices from online retailers, or system alerts (like mailbox-full alerts, one hopes), that often clutter up in-boxes could clean themselves out.

Baer hopes that the audience members at this conference, all of whom are in the e-mail business, start supporting his proposal. In the meantime, he says, his own e-mail organizing service (which I use and recommend) will start watching for and honoring expiration flags in e-mails it processes.

There's a Google group for the proposal. See also this Reporters' Roundtable with Baer: Does e-mail get the message.