Example: Heads up! It appears that JOE at COMPANY recently left. Check their {{LinkedIn URL}} to confirm.
Subject: Did JOE leave COMPANY?
Hi {First Name}, I noticed that JOE no longer seems to be working with COMPANY. I had a great time working with JOE and I’m sure you miss his company. I understand you might still be busy with staying on top of everything. Considering this and ensuring continuity with the YOUR COMPANY evaluation, please let me know if there is anyone I should involve.