The subject line matters, but not in the way most people think. You're not trying to be clever or witty. You're trying to tell someone why they should stop what they're doing and read this particular message right now.

Look at your own inbox. The emails you open are the ones that either solve a problem you have or promise information you actually need. Everything else gets ignored or deleted.

There isn't one. It depends entirely on what you're sending and who you're sending it to. If every email has something useful, people will want to hear from you more often. If you're just filling space, once a month is too much.

The better question is whether each email justifies itself. Does it contain information your subscribers actually want? If you can't answer that honestly, you probably shouldn't send it.

Segmentation makes sense when you have genuinely different things to say to different groups. If you're selling both gardening tools and cooking equipment, those audiences probably want different emails.

But don't overcomplicate it. Most businesses can start with two or three basic segments based on what people actually bought or showed interest in. You can always get more sophisticated later if the data shows it's worth the effort.

Long enough to say what needs saying, short enough that people will actually read it. Some messages need three paragraphs. Some need ten. The length isn't the issue, clarity is.

Most emails could be shorter. Cut the introduction that explains what you're going to explain. Cut the conclusion that summarizes what you just said. Get to the point, make it clear, and stop.

Open rates tell you if your subject line worked. Click rates tell you if your content was relevant. But the real measure is what happened after the click. Did people do what you wanted them to do?

Track the whole path. An email with a low open rate but high conversion might be more valuable than one with high opens but no action. Context matters more than any single number.