I remember when people paid for newspapers. Now, it seems, they can’t even give them away.
The problem was, when newspapers such as the Manchester Evening News became free (which it was in the city centre up until recently), the perception of the paper took a beating.
Yes, circulation levels went up, but then attention levels went down. This meant that advertising space was valued at even less than it was before the price crash (when the paper had smaller circulation figures).
This is typical of over-used media
If you devalue your message by giving it away, then, by its very nature, the value has reduced. This is the same with emails.