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In the modern era, lots of mailservers run software that looks for weirdnesses in incoming email. I don't know, but I'd suspect that the typing delays of using
by greglindahl 7y ago
In the modern era, lots of mailservers run software that looks for weirdnesses in incoming email. I don't know, but I'd suspect that the typing delays of using telnet to send mail are likely to trigger their defenses.
- bigiain 7y agoSO I just tested. After working out that on macOS I now need to use nc -c instead of telnet... I _can_ send mail manually, but it _does_ end up in gmails's spam folder saying "Why is this message in spam? It is similar to messages that were identified as spam in the past." Iain-2:~ iain$ nc -c gmail-smtp-in.l.google.com 25 220 mx.google.com ESMTP k5si5682618pls.209 - gsmtp EHLO elided.org 250-mx.google.com at your service, [202.171.181.100] 250-SIZE 157286400 250-8BITMIME 250-STARTTLS 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-CHUNKING 250 SMTPUTF8 MAIL FROM: <bigiain@elided.org> 250 2.1.0 OK k5si5682618pls.209 - gsmtp RCPT TO: <bigiain@gmail.com> 250 2.1.5 OK k5si5682618pls.209 - gsmtp DATA 354 Go ahead k5si5682618pls.209 - gsmtp Subject: Test From: bigiain@elided.org To: bigiain@gmail.com Date: Fri, 31 Jan 2020 13:07:00 +1100 Foo baz nah . 250 2.0.0 OK 1580436443 k5si5682618pls.209 - gsmtp QUIT 221 2.0.0 closing connection k5si5682618pls.209 - gsmtp Iain-2:~ iain$
- wolco 7y agoI wonder why google treats this simple email as spam. It contains nothing that should trigger the spam filter aside from where it came from.
- greglindahl 7y agoMost mailservers don't send emails one character at a time. You appear to have a mental model of how a spam filter works that doesn't include fingerprinting the behavior of the sending server? Even open source mail servers do that, for example postscreen is a part of postfix.
- bigiain 7y agoI wonder if it'd fare better if I scripted nc with expect? (Not sure I care enough to try...)
- duskwuff 7y agoSome of the things it doesn't contain, though -- like Message-ID and Content-Type headers -- are likely to contribute to its spam score. If your domain has SPF headers which don't permit mail from the (residential?) IP you're connecting from, that'll be a major factor as well.
- nrb 7y agoWhere it came from is one of the most important details! Is this mail relay actually elided.org or is it impersonating elided.org? There does not appear to be an SPF record for that domain so Gmail cannot determine if this is a fraudulent message, especially if the machine this request came from does not match the IP of the A record for that domain.
- arein2 7y agoSome years ago I wrote my email in a forum, available to crawlers. I’ve been getting spam ever since.