Two flat prices, two different meters
Both of us decided that charging per person is the wrong way to price email. Where we parted company is what to charge for instead.
Migadu picked throughput. Their tiers are defined by messages per day — 200 in and 20 out on Micro, 1,000 in and 100 out on Mini — and storage is deliberately soft, with no hard quota, so your mail will not bounce because a mailbox filled up. That is a genuinely kind design decision and we do not match it.
We picked storage. Ten gigabytes pooled across everybody is included, more is $0.40 per gigabyte per year, and there is no tier that depends on predicting how much mail you will send next year. Both models are honest. They are bets on different things being scarce.