To the question, ‘Is email deliverability an exact science?’ the answer is No and No. If it was either exact or a science it would be possible to ensure that our marketing emails were not classed as spam. But it’s not, and we have to work within that limit.

It means there is no definitive answer to why a particular email ended up in one subscriber’s spam folder yet sailed through to the inbox of another. It depends on numerous variables. What we can do is limit the chances of our emails being rejected by ensuring we are doing the basics correctly and avoiding the temptation of what appears to be a cheap fix.

Start by developing a strong foundation for your email marketing list; but you probably knew that already. You might be confused as to how you should go about it. The answer most commentators give is to build your own email marketing list, gathering subscribers with open, clear and honest methods. Follow that advice and you’re almost there.

There are few things in email marketing that one can suggest you should never do, and I’m sure of none. I will tell you, though, that I have never rented, bought or co-registered an email list, nor shared a list with a partner. My reasoning is that the medium-/long-term costs exceed any benefits.

We should also verify whether a new subscriber has understood what they’ve signed up for by providing a double opt-in. There is, obviously, a risk that the subscriber will change their mind, but better for us now rather than later when they’ve classed our marketing emails as spam. We’ll address what’s the best format for the double opt-in email another time.

The work in ensuring that your email marketing list is pristine hasn’t ended there as you now have to ensure that you keep it that way. It’s not much bother. Deleting non-performing subscribers removes those who no longer respond or even open your emails. It also ensures that your delivery rate is actually dependable data. While a large email marketing list is a target that we all seek to hit, if some on it are unengaged, the actual figure will mean little and can confuse other data.

Once you have a clean list you can depend more on your metrics. The most important aspect that you have complete control over is sending relevant content. There’s not much point in sending offers your subscribers have no interest in, yet bewilderingly it is something that most email marketing companies indulge in from time to time. Don’t do it.

One of the most valuable assets any email marketing company owns, perhaps the most, is their email marketing list. Ensuring that it is based on consent and compliance with the GDPR is a major factor in avoiding the spam folder. Regular maintenance is required to keep it performing well.

This is a basic overview and we will return to it from time to time as it is an essential for our business models.