I did a test recently and sent the same email several times to small business retailers using POS software from my software company.
Clicks on links on the third send were almost as good as the first time. I could tell from the mail software that the clicks were from different businesses too.
The experience told me there were plenty of people who missed emails, that there was a case to be made for sending information/news emails more than once.
My management tip today is – have an email policy. Manage emails to ensure they are all read. Otherwise, you could miss important information.