Employees at the little Stinson Beach Post Office are coming up for air now that a tsunami of ticket requests — many in elaborately decorated envelopes — for the Grateful Dead’s 50th anniversary concerts has slowed to a trickle.

More than 60,000 pieces of mail have flooded the beach side post office since mail order tickets went on sale Jan. 20 for the Marin-based band’s three Fare Thee Well concerts July 3 to 5. The shows will be in 55,000-capacity Soldier Field in Chicago, site of the Dead’s final 1995 concert with paterfamilias and lead guitarist Jerry Garcia, who died a month later. The concerts reunite the original band members for the last time.

“We got inundated with far more requests than anyone expected,” said postal clerk Mark White. “They (the ticket staff) like to give us an idea of how many they’re going to get when they do these shows, but the fact is there hasn’t been a show of this calibre for a long time.”

Apparently, the band was as surprised as the postal service by the overwhelming demand for tickets, priced at $59.50 to $199.50.

“Wow! We’re excited (and humbled) to discover that your enthusiasm for Fare Thee Well matches our own,” according to a statement online at dead50.net. “In an effort to honor the history and spirit of the Grateful Dead, we’re going to try to fill as many of these orders as possible.”

Because there have been far more requests than available tickets, the post office is now handling 2,000 to 3,000 outgoing rejection letters a day to disappointed Deadheads.

“That isn’t a problem, because they go out with our regular mail,” White said. “But it was a problem when we were getting 15,000 to 20,000 envelopes with tickets requests in one day. We’re a very small office.”

If ticket requests comply with Grateful Dead Ticketing Service (GDTSTOO) instructions, they go into a lottery so that everyone has the same chance of getting them. To give the staff time to process that many orders, the date for tickets to go on sale to the general public via Ticketmaster has been pushed back from Feb. 14 to 10 a.m. CST Feb. 28.

In keeping with a tradition dating back to the early 1980s, when the band began its mail order ticket service in Stinson Beach, Deadheads believe they have a better chance of winning the lottery if they decorate their envelopes with hand-drawn Grateful Dead iconography like dancing bears, skull and roses and the “Steal Your Face” image, aka “Stealie” — a blue and red skull with a lightning bolt slashing through it. The phenomenon inspired “Dead Letters: The Very Best Grateful Dead Fan Mail,” a 2011 book by Paul Grushkin.

“The artwork is incredible,” White said. “A good third of them are detailed with artwork that must have taken people a lot of time. The amazing thing that I discovered is that it’s not just older people, but some of them have written on the envelope, ‘Third generation Deadhead.’ It’s the kids of the kids.”

That kind of diversity was the original motivation for the creation of GDTS TOO by then band manager Danny Rifkin, according to Dennis McNally, the Dead’s official historian. By the early ’80s, Rifkin recognized that a large number of Deadheads had gotten older, had jobs and families and were no longer willing to drop everything to stand in line all night at Ticketmaster outlets to buy tickets when they went on sale in the morning.

“The idea wasn’t to make a lot of money,” McNally said. “The idea was to diversify the band’s audience. And it worked like a charm.”

For the three final shows, original members Bob Weir, Phil Lesh, Bill Kreutzmann and Mickey Hart will be joined by pianist Bruce Hornsby, keyboardist Jeff Chimenti, and lead-guitarist-singer Trey Anastasio of Phish.