The Gov.uk site, https://www.gov.uk/, which provides government guidance and services, such as vehicle tax payment, has succeeded in what is probably one of its main intents by saying that it will phase out Latin abbreviations, such as eg, ie, etc, et al (sorry. Too tempting to resist.) It created a small furore in the press, with headlines that frequently included 'Bans'.
The reasons behind the move was not solely to generate clicks but to make the web content easier to understand for everyone, including those for whom English is not their primary language. Having a background in law, I am used to certain Latin phrases and abbreviations. Why else would I know what ejusdem generis means?
You probably have your own opinion as to whether this is a good move or not but it brings up a very valid point: communications should be worded so that those it is aimed at will understand it. For instance, the middle phrase could have read 'those at whom it is aimed'. Which would you consider as most readable? More importantly, which would the subscribers to your email marketing list prefer?
Abbreviations can be extremely useful in online copy. It's a way of making it quicker and easier to read so should be one of the targets you strive for. I'm all for them. Indeed, the Gov.uk point is well made.
It is an information site in the main and much of its content would be well known by those brought up in this country. It is probable that a significant proportion of their readers will be new to the UK or will not have English as their first language. In addition, I am assured by an Australian friend that Latin isn't that big Down Under.
In other words, they are writing their copy in order to be understood by their readers. Isn’t this an essential for email marketing?
Whether you follow Gov.uk's example will be down to the makeup of your email marketing list. It is probable that for some it would be useful, for others it would be irritating.
A danger can be that copy will be dumbed down and there's little that is more irritating than patronising language. It is just a case of balance. The simple answer is to write in plain English.
The Plain English Campaign, http://www.plainenglish.co.uk/ provides a number of free guides to help with such matters as writing clearly. There is also a guide to alternative words, not so much a thesaurus as a means of making copy easily understood.
There are examples of clear copy as well as gobbledegook. Some of the latter will make you wonder why anyone should waste so much time being obscure.
One particular item is rather useful at the moment. It is a post Brexit guide to what might happen: http://www.plainenglish.co.uk/news/1244-we-voted-leave-what-now.html
Many email marketing companies already follow the plain English route. For products like printers or cameras, the copy is kept simple and there's a click-through to the technical information for those who want to go deeper.
Remember that if people don't understand what you've written, it is your fault.