This is legit. It's a service that our library--and apparently others--use for reserving study or conference rooms online. When you confirm your reservation, you receive a confirmation text. If it doesn't apply to you, then perhaps the real person reserving the room entered the wrong phone number.
same as other user:
"D!BS! Your request for Study Room #1 in Orange Branch Library on 9/22/2015 9:00 AM is confirmed.
Sent using SMS-to-email. Reply to this email to text the sender back and save on SMS fees.