> Gmail rejects outgoing email from most home ISPs
The configuration must go with the flow, for example it's recommended to at least configure SPF or DKIM. For each E-Mail a score will be calculated and both make it better, there's also DMARC for further improvement. In fact not only Gmail does this, most non-trivial mail setups do inbound filtering.
Nowadays there are even Docker containers for that. Not saying that E-Mail is great but automation will get one really far and there doesn't seem to be a decentralized alternative for that yet. (Obviously there are centralized alternatives; and of course there's XMPP)
The configuration must go with the flow, for example it's recommended to at least configure SPF or DKIM. For each E-Mail a score will be calculated and both make it better, there's also DMARC for further improvement. In fact not only Gmail does this, most non-trivial mail setups do inbound filtering.
Nowadays there are even Docker containers for that. Not saying that E-Mail is great but automation will get one really far and there doesn't seem to be a decentralized alternative for that yet. (Obviously there are centralized alternatives; and of course there's XMPP)