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Most, if not all, residential IP blocks are in the various blacklists most mail servers query. Merely having a reverse PTR won't get your email delivered. Even SPF and DKIM with DMARC probably won't be enough to get over the blacklist rating.

Some business IP blocks aren't blocked, though, so in rare cases you might get away with running a mail server from a business internet subscription.

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> Even SPF and DKIM with DMARC probably won't be enough to get over the blacklist rating.

I can confirm this. I recently tried to set up being able to send emails from an smtp server in my homelab to my gmail address. Even with all the good stuff - a domain, tls, spf, dkim, dmarc, gmail just straight up refuses to receive mail from residential IPs. I ended up proxying it through my VPS, which works better but still requires me setting up gmail rules to NEVER send messages from my special domain to spam. Which it would otherwise do for no apparent reason sometimes.

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