3 ms·

And sometimes if you do everything right, it still doesn’t work. Recently I checked the IP against blacklists, waited a few months, did all of the other things

And sometimes if you do everything right, it still doesn’t work. Recently I checked the IP against blacklists, waited a few months, did all of the other things, and then found out Microsoft bounces my entire VPS’s IP range. Appealing did not help. They intermittently block Cloudflare email routing IPs too. All of these security measures and still it comes down to the IP address of your sender.

1over137 3mo ago
Is it an el cheapo VPS?
- doubled112 3mo ago
  Is Cloudflare a cheapo VPS? It is a cheap VPS, but it would still be nice if there was a way to know (not assume) beforehand. > 550 5.7.1 Unfortunately, messages from [IP ADDRESS] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). > Your IP(s) qualify for conditional mitigation. Still blocked. The system is working as expected.
  - jeffbee 3mo ago
    I would simply like to point out that 550 at SMTP time is not a bounce.
    - doubled112 3mo ago
      You get an email bounce back with an error code in it. Is there some other definition I'm unaware of? Wait, that is probably from the local mailer, and otherwise the sender may never know about the rejected messages.
    - b112 3mo ago
      5xx are bounces, a perm failure. 4xx error codes are temp (retry) errors.
      - jeffbee 3mo ago
        Incorrect. A bounce is a delivery status notification generated by a mailer after it has already accepted a message for delivery. A 5xx permanent error is a refusal to accept the message in the first place.
        TZubiri 3mo ago
        Is this standarized terminology in some RFC like SMTP? Or is it presumably some well established folk lingo?
        b112 3mo ago
        They're referring to the bounced notification message, not the fact that the mail bounced. Verb and noun. A 5xx is a bounce, and results in a bounced email message. Variances always abound, but I'll stick with my 30 year old terminology, and it is correct.
        jeffbee 3mo ago
        That's fair with regards to your statement, but "doubled112" assigned the agency to Microsoft, saying that "Microsoft bounces" their traffic, which is demonstrably not what is happening.
        b112 3mo ago
        It is what's happening, as I've described. A 5xx is a bounce. You don't agree with my terminology, but we're not disagreeing on what's happening. In this case, as per my dictionary, 'rejected' and 'bounced' are synonyms. If this was me, and my MTA hitting this Microsoft server, my MTA/server would see the bounce(5xx), then my MTA/server would generate a bounce message(email) which I'd receive in my inbox. The bounce message is a result of the bounce. The action/cause is the bounce/reject 5xx. How can you have a bounce message, without a bounce happening? Again, you don't agree with this terminology, and that's fine. But I'm not pulling this out of a random hat, it's 30+ year old terminology that I've used with endless people locally and online. That doesn't mean your view is wrong, we may just be running into local variances in lingo. There are all sorts of edge cases in our compute discourse. I ran into a company where they didn't use initialisms to discuss daemons/protocols, but treated them as acronyms. Of course, they didn't really discuss such things often. So when discussing smtp, they'd pronounce it 'sim-tee'. Of course, sntpd, smtpd, snmpd, and others are all pronunced 'sim-tee', which makes for a fun meeting. Think of it as 'I am groot' taken too far. For prudence, I kept enforcing initialisms, which of course resolved this. Anyhow! Point is, well.. not really sure except info.
  - inigyou 3mo ago
    Cloudflare is one of the shadiest hosts around, almost as bad as the big three clouds.
  - TZubiri 3mo ago
    You can't have the cake and eat it too. Either you use cheap infrastructure that attackers can buy by the bulk for sybil attacks. Or you pay a reasonable price for a slice of an IP block that doesn't share its reputation with elcheapos.
    - doubled112 3mo ago
      No disagreement here. I had never planned to use it for email, but I was bored and I already had it when I got an idea.

1over137 3mo ago

Is it an el cheapo VPS?

doubled112 3mo ago
Is Cloudflare a cheapo VPS? It is a cheap VPS, but it would still be nice if there was a way to know (not assume) beforehand. > 550 5.7.1 Unfortunately, messages from [IP ADDRESS] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). > Your IP(s) qualify for conditional mitigation. Still blocked. The system is working as expected.
- jeffbee 3mo ago
  I would simply like to point out that 550 at SMTP time is not a bounce.
  - doubled112 3mo ago
    You get an email bounce back with an error code in it. Is there some other definition I'm unaware of? Wait, that is probably from the local mailer, and otherwise the sender may never know about the rejected messages.
  - b112 3mo ago
    5xx are bounces, a perm failure. 4xx error codes are temp (retry) errors.
    - jeffbee 3mo ago
      Incorrect. A bounce is a delivery status notification generated by a mailer after it has already accepted a message for delivery. A 5xx permanent error is a refusal to accept the message in the first place.
      - TZubiri 3mo ago
        Is this standarized terminology in some RFC like SMTP? Or is it presumably some well established folk lingo?
        b112 3mo ago
        They're referring to the bounced notification message, not the fact that the mail bounced. Verb and noun. A 5xx is a bounce, and results in a bounced email message. Variances always abound, but I'll stick with my 30 year old terminology, and it is correct.
        jeffbee 3mo ago
        That's fair with regards to your statement, but "doubled112" assigned the agency to Microsoft, saying that "Microsoft bounces" their traffic, which is demonstrably not what is happening.
        b112 3mo ago
        It is what's happening, as I've described. A 5xx is a bounce. You don't agree with my terminology, but we're not disagreeing on what's happening. In this case, as per my dictionary, 'rejected' and 'bounced' are synonyms. If this was me, and my MTA hitting this Microsoft server, my MTA/server would see the bounce(5xx), then my MTA/server would generate a bounce message(email) which I'd receive in my inbox. The bounce message is a result of the bounce. The action/cause is the bounce/reject 5xx. How can you have a bounce message, without a bounce happening? Again, you don't agree with this terminology, and that's fine. But I'm not pulling this out of a random hat, it's 30+ year old terminology that I've used with endless people locally and online. That doesn't mean your view is wrong, we may just be running into local variances in lingo. There are all sorts of edge cases in our compute discourse. I ran into a company where they didn't use initialisms to discuss daemons/protocols, but treated them as acronyms. Of course, they didn't really discuss such things often. So when discussing smtp, they'd pronounce it 'sim-tee'. Of course, sntpd, smtpd, snmpd, and others are all pronunced 'sim-tee', which makes for a fun meeting. Think of it as 'I am groot' taken too far. For prudence, I kept enforcing initialisms, which of course resolved this. Anyhow! Point is, well.. not really sure except info.
- inigyou 3mo ago
  Cloudflare is one of the shadiest hosts around, almost as bad as the big three clouds.
- TZubiri 3mo ago
  You can't have the cake and eat it too. Either you use cheap infrastructure that attackers can buy by the bulk for sybil attacks. Or you pay a reasonable price for a slice of an IP block that doesn't share its reputation with elcheapos.
  - doubled112 3mo ago
    No disagreement here. I had never planned to use it for email, but I was bored and I already had it when I got an idea.