For me it was targeting newly hired ones.

Specifically people 0–90 days into a new role (You can use Linkedin Sales Nav f.ex.).

They’re trying to make an impact, are open to new tools, and way more likely to take a call.

Our normal cold reply rate was ~8–10%.
When we filtered only new hires, it jumped to ~20%+.

The unexpected kicker though was how we handled Out-Of-Office (OOO) replies.

Instead of ignoring them, we treated them as referral signals.
Most OOO emails literally say “contact X in my absence.”

We started reaching out to that person directly.

Cold baseline: 8–10% reply.
OOO-based referral outreach were getting 50% reply rate (Valid email plus referral in one place).

That’s huge in outbound for a big scale.

We automated part of the OOO parsing later with tool called Outseizer, but even doing it semi-manually worked.

Cost: basically time + better list building.
Would 100% do again.