Hi - Has anybody found any effective masterclasses/guides on cold-emails, specifically within the context of search? We've found a few other resources, but they are primarily geared towards salespeople (with a slightly different sales pitch). In particular, we're looking to answer a few key questions like:

1. What is the best subject line (for response rates, not just open rates)
2. What is most effective for the initial email (length, level of personalization, how much of a pitch)
3. Ideal times to email owners to maximize open and response rate
4. How many times should one email / length somebody in an optimal campaign