From Chapter 11 of the Big Red Book of ACA, page 365-390:

ACA Meetings can act as a sponsoring influence.  The groups that sponsor a person indirectly usually emphasize the Twelve Steps, Twelve Traditions, sponsorship, other program tools, and offer a well-stocked literature table with a phone list.  The meetings are friendly and focus on recovery.

Step Study Groups that meet regularly to work the Steps together can provide indirect sponsorship.

Service Boards or Committees should not be used as a replacement for traditional sponsoring, but these boards and committees can mentor healthy behavior and offer sponsorship influence.

ACA Arizona has a great page on their website detailing the “Fellow Traveler” approach. Check it out here.