Custom audiences launched: upload email and phone lists to include, exclude or bid-adjust matched users

OpenAI introduced custom audiences for ChatGPT Ads, letting advertisers upload first-party customer and prospect lists (emails, phone numbers) to target or suppress at the campaign level and apply bid adjustments to matched users at the ad group level. Lists initially required 25,000 or more members.

• Eric Seufert called the feature 'critical plumbing' and 'table stakes' for a modern ad platform.
• September updates added incremental list edits, mixed identifiers, GAID support, sub-25K exclusion lists and audiences above 5 million.