The open rate returns from your email marketing software might have given your confidence a boost when you checked them against those from the previous campaign. The subtle changes you made to the Subject line were obviously a brilliant idea and all that remains is to tell your boss. However, you might be missing a trick.
The subscribers to your email marketing lists probably came from a number of sources. There was that counter promotion where your staff got a little bonus for every 100 email addresses they got. Then there was that trade fair that was a major investment but, given the increase to your email lists, it was worth every penny.
It is probable that each source provided subscribers with certain characteristics in common. For instance, those that came via your website are likely to, on average, be more internet savvy than those you obtained via the gardening gloves competition. Therefore it can be useful to divide your email marketing lists along the lines of where the subscribers came from.
A Subject line that interests one group could well be a turn-off for another. The difference might be small but a 1% increase in open rate is good news. You will never know unless you test. Not to do so is to ignore the potential of your email marketing software statistics.
Further, one of the lists divided by source might well provide a very low open rate. If, for instance, this was from an advert in a magazine for the fashion conscious it could be that they are using smartphones in order not to be ostracised, so showing as a negative. To find out, compare the click-through rate of this group with another or the norm. If there is little difference then you can rest more easily.
If those on your email lists do not open their emails then all the effort you put into the offer and the design is wasted. You need to get it past this barrier. Whilst the overall open rate is a useful pointer, the more you refine your data the more you will be able to direct your resources effectively.