Why? It's their business. You didn't sign a contract saying "free for life". It's sad, but there is no free lunch, and you shouldn't build your own business off the assumption that some resource will be free forever.
Free tiers are just another type of market research where the company is collecting data to determine the stickiest features.
$8 (or less) per month to keep using the feature with competition (sending). $35 a month to keep using the feature without competition (receive filtering and forwarding). Is that a coincidence?
$8 (or less) per month to keep using the feature with competition (sending). $35 a month to keep using the feature without competition (receive filtering and forwarding). Is that a coincidence?