The defunct band packages its complete "Unplugged" sessions, with plans to make future releases special. "I mean, if we've been sitting on stuff for this long, why go cheap with it now?" says Mike Mills

A continuing series of vault-trolling archival releases, with more on the horizon, have made it easier to cope with R.E.M.'s abrupt 2011 split, according to the group's Mike Mills.

"It's nice in the sense that it keeps our breakup from being a cold, hard ending," Mills tells Billboard. "It softens the landing a little bit. It's like, no, I don't get to record with Peter (Buck), Bill (Berry) and Michael (Stipe) anymore, but we get to just remind ourselves of how much fun we had."

R.E.M. has released deluxe editions of most of its albums, expanded to include unreleased studio and live material. The group'a latest project is "Unplugged: The Complete 1991 and 2001 Sessions," taken from its two MTV "Unplugged" appearances. The 33-song set, which features 11 songs that were never broadcast, came out on vinyl for this year's Record Store Day and was released on CD and digital download today, May 19.

"They've been sitting there for awhile, and I guess we just never thought there was a right time to release them until recently," says Mills, who signed copies of the vinyl edition at Bull Moose Music Warehouse in Portland, Maine on Record Store Day. "We've always supported Record Store Day, and it just seemed like a perfect match-up of stuff that we had and stuff that they needed. And it's good to put it out as we wish to let it out; bootlegs are great and I love 'em, but it's nice to put your stuff out in a way that you would like to have it presented."

Mills says going through the "Unplugged" material brought back good memories, though he says that preparing songs in that format "really wasn't very difficult. The way we wrote...the songs can hold up to being done in a stripped-down manner, without all the volume or the studio bells and whistles. We just take all our instruments and make them acoustic; it was literally that simple. It didn't take a whole lot of reworking, but we did see it as a challenge to take these songs that people pretty much knew only in an electric format and have them work acoustically."

Mills says R.E.M. hasn't decided yet what its next archival release will be, but he's confident it won't be long before the discussion starts.

"We have a lot of stuff in the vaults, a fair amount of stuff that's never been released," Mills confirms. "We all want to do something with this stuff. We know we've got some really good things hanging around. We just want to put them out in a way that makes them as special as possible, because they're special to us. I mean, if we've been sitting on stuff for this long, why go cheap with it now? Let's try to make it be special rather than just dumping out the vaults."

Mills -- who's currently playing with the Baseball Project and the New Professionals and is planning a "combination of classical and rock 'n' roll" project -- says he runs into Buck and Stipe "at all kinds of places" and stays in touch with Berry by phone. But, he assures us, R.E.M.'s resolve in being broken up has not wavered. "We're all happy pretty much as clams," Mills says. "Everybody's busy and really having a great time. It's a nice relief in a way; as much fun as it was, it's nice to not have to be on the hamster wheel anymore."