Avoiding spam filters and ISP blocks are a common issue with self hosted email.
Ideally you’ll have a mature domain, dkim configured and an IP that’s not blacklisted on a network that allows email traffic.
OVH offers pretty cheap email hosting if you just want a turn key solution.
Otherwise if you want your home lab to work this way you may need to configure something akin to a forward proxy on a VPS to act as a gateway for your homelab.
This could be achieved using wireguard and iptables. By routing the email traffic to your homelab.
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