Workaround that gets close: Clay → ABM List → LinkedIn DM Ads.
Build your enriched list in Clay, export as CSV with LinkedIn profile URLs or company domains, upload as a matched audience in LinkedIn Campaign Manager, then run Conversation Ads (their DM ad format).
Not 1:1 InMails, but you're hitting the same inbox with targeted messaging at scale. Plus you get LinkedIn's reporting vs blind InMail sends.
Main trade-off: ad spend vs InMail credits. But if you're doing volume, often cheaper per-touch anyway.
