Bored of the games on your computer? Then spend some time on a fruitless google search – “email subject lines length” should do the trick nicely. You can even claim it as research if your boss wanders by.

The web is full of helpful advice on the subject. Most often you’ll be told that shorter is better. But then again, many sites will tell you that longer actually improves opens and click thrus. And because we all like to keep it simple, others will tell you that a certain number of characters is the answer. Feels a bit too much like The Hitchhikers’ Guide To The Galaxy to me. So what’s my opinion?

There is no simple answer; it depends. There, I’ve written it. Your subject line should be the shortest that gets your message across successfully and makes your reader act. But that does mean that it may have to be quite long on occasions.

And that is the point; a subject line is not some scientific equation; it is an invitation to a dialogue. To be successful it requires a balance of factors. Just like the first line in a conversation, it needs to consider who it is speaking with (note the word “with”, not “to”). It should engage and avoid the types of words that frighten people off.

So make sure they are enticing, with key words upfront (remember mobile readers), aren’t spammy and give a reason to click thru and continue the dialogue.

Finally, never forget that your prospects and customers are human and will react differently from the email average. Remember the mantra: test, test, test.