Just to add another (probably minor) issue that occurred to me today on reading Juggling TidBITS Infrastructure Issues: Presumably if you switch away from SendGrid (whether now or in 20 years), the links in existing email issues will stop working. There’s probably no way around this, and it probably doesn’t matter (lots of links die anyway), but as I archive every email issue of TidBITS, it makes me just a bit sad. 