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Good day, I set up SMTP server I am using sendinblue SMTP also I checked my email score with https://www.mail-tester.com/ and scored 8.9 from 10. I lose 1.1 point on reverse DNS but I think I just need to wait till DNS will update. But some of my clients who use web.de or yahoo cant get security emails from my domain. I checked if I am in black list but my IP is not there. Where could be the problem ?
Mārcis
Posted 2019-07-29T12:40:55.223
Reputation: 1
2If a mail server refuses to accept mail from your server, it will give some message hinting at what is wrong (some really spell it out). So first thing to do is to check your own mailserver's logs. – wurtel – 2019-07-29T12:47:38.777
1@wurtel not neccessarily or even generally true. In many cases the email is silently eaten so as not to cause backscatter due to forged from addresses. This sounds to me like emails may be being misclassified as spam thanks to phishing emails claiming your account may be compromused and telling you to click on $phishing link to fix/reset. Those silently go straight to spam on many setups. – davidgo – 2019-07-29T19:47:20.393
1@davidgo backscatter only occurs if the mail is not rejected at SMTP time, as it should. Either accept the message or reject it, don't first accept it and then send a DSN. Anyway, I still assert that the first place to start looking for clues why your mail is not received is to check your own mail logs. If the logs tell you that the message was simply accepted by the remote server, then you know who's causing the problem. – wurtel – 2019-07-30T06:30:16.407
1@wurtel With respect of SMTP you are only partly correct and there are A LOT of reasons mail servers dont reject when a connection is made - chief among them being that it is extremely costly in terms of immediate processing requirements and threads - in reality no large mail server can afford to do this and most mail servers are modular and dont work well with this model. Also, I am not aware of suitable error codes for a DATA payload to be classified as spam. Further many servers are just relays/buffers/queuing servers. – davidgo – 2019-07-30T08:40:37.767
@davidgo any providers who consider email to be an important service should invest in the service. It's also not much more costly to immediately run checks in incoming mail at SMTP time, it's perhaps a bit more complicated. All mail servers I've installed (quite a few) do this and can handle lots of email. 90% don't even hit the spam filters but is rejected because of errors in headers or wrong HELO names, for example. Anyway my point is still: check the outgoing logs, which you didn't protest against so I assume you agree. Let's agree to disagree on the rest. – wurtel – 2019-07-30T09:09:20.450
@wurtel Disagree, and indeed Im skepticalbyou have set up large (thousands of clients+) servers. The guys behind Postfix and Sendmail know there stuff and power a lot if large installations despite your dislike of how it works. The RFC's for email are quite specific about assuming mail in the DATA section to be valid, which is at odds with your belief. (And yes, I am aware of blocking based on IP and headers, and abuse greylisting to boot). Checking logs is never a bad idea but is unlikely to be of much help as to ehy emails are silently dropped as the OP describes. – davidgo – 2019-07-30T09:19:36.427
I refer you to ahttps://tools.ietf.org/html/rfc532#section-4.1.1.4 which fairly authoratively dictates when servers.send a 250 and when they send something else - and classification of SPAM is nit a reason for rejecting, likewise.it is assumed mail.may be relayed,.
– davidgo – 2019-07-30T09:24:27.967