Then I would try to implement that since if users don't want emails this could be considered a spam message and one could get into trouble. I created a Mail Chimp account and they wanted your home address due to this. Luckily I have an extension that tells me who has or doesn't have the contact by admin preference off among other things. So in the extension I can download the CSV and tailor it to not include those emails.
Spam is in the eye of the beholder...
I don't consider it as spam.
The board will send it once every x amount of days for 3 times and then it will stop.
It is to remind the member that he/she has an account and that if he/she will not visit again the board it might result to a deletion of the account.
However I will consider it on next releases to implement it as an option.
Thank you for your suggestion!