You should check to see if the messages that are being sent contain any links that would be considered questionable/spammy. You can also try taking the content of one of the messages and checking it’s spam assassin score ( https://spamcheck.postmarkapp.com ). Source: over 2 years ago

Build a clean email that passes a spam check with flying colors (https://spamcheck.postmarkapp.com/) then use a warmup service like lemwarm, inboxally or neverspam as mentioned in the other comments. Source: almost 3 years ago

The issue sounds more email centric. You're likely hitting the Apache SpamAssassin limit on the remote email servers. Use https://spamcheck.postmarkapp.com/ to check the score of emails you've had declared spam, and follow recommendations to improve. Source: about 3 years ago

Sshuttle - Open source project originally from one of the founders of Tailscale. Server doesn't require root; client does. Explicitly designed to avoid TCP-over-TCP issues. - Source: dev.to / 2 months ago

Https://github.com/sshuttle/sshuttle with bastion. Source: over 1 year ago

Sshuttle seems to do the job but its not available for windows. Source: over 1 year ago

This is excellent but I would give a shout out to sshuttle which can make a lot of this stuff even simpler. Source: over 1 year ago

That's really good to hear! They got a (well deserved!) 100M investment recently. I didn't know it until recently, but apenwarr made some of my favourite tools (sshuttle, bup) and now tailscale! If you come across the podcast again, please post the link, I'd love to listen to it. Source: over 1 year ago