1. It’s short and what he’s requesting is clear. No “let’s jump on the phone for 10 minutes; it’ll be worth your time.”
2. He made an impression in our initial meeting, and he hasn’t irritated me with zero-content “keeping in touch” e-mails. He hasn’t worn out his inbox welcome.
3. He makes it clear that he’s doing his part and has explored other avenues before asking for my help. It’s amazing how many would-be mentees or beneficiaries ask busier people for answers Google could provide in 20 seconds. That puts you on the banned list. Explicitly state what you’ve done to get answers or help yourself.
4. He used the executive recruiter referral trick. Seldom will a headhunter call a gainfully employed CXO-level executive and ask them to take another position. They’ll instead ask the exec if they know anyone who might be interested in position X. The intention is clear (might you consider this job over your current employer?), but it gives the executive a comfortable decline option.
5. He makes it clear that it’s OK if I can’t help or if I’m too committed elsewhere. This — paradoxically — makes it much more likely he’ll get a response, which he did.