Yes, from the Auctions Bidders grid you can text all the bidders from the Actions menu. Click on Send Text Message.

Enter the text message info and choose to send the message immediately or prepare texts and schedule them to go at specific times. Note that the time/date selected is not a guaranteed delivery time. The constituent's messaging service provider determines when the actual message is delivered. If you have very time sensitive messages, be sure to schedule their delivery with some margin for delays by their service provider.

Note that there is a maximum of 2000 direct text messages per day. The automatic messages sent via the auction process do not count towards the 2000 total. Only those messages generated manually count toward the total.