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Only mail servers should be talking on port 25. Clients should be using 587 to talk to servers. I've never had an issue with any ISP nor VPS provider with port

Only mail servers should be talking on port 25. Clients should be using 587 to talk to servers. I've never had an issue with any ISP nor VPS provider with port 25. You can't expect hotels and inflight internet providers to allow you to run a mail server inside their perimeter, they do block 25, but I have never had a problem with 587.

zaarn 9y ago
Problems with 587 usually come from Snakeoil^w AntiVirus software that wants to intercept your email traffic to scan for potential malware. Obviously it doesn't have the certificate so some bruteforce it by only allowing plaintext. On 587.
0xffff2 9y ago
Every home ISP I've had in the last 10 years also blocks 25. Why shouldn't I be allowed to run a mail server from my home?
- dorfsmay 9y ago
  This hasn't been my experience. I'm assuming you've check the FW rules in their modem/router?
  - 0xffff2 9y ago
    More to the point, I've talked to second line tech support agents who have told me that they block all incoming connections on port 25 as a spam prevention measure.