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Comment Re:Anti-Spam Measure? (Score 1) 245

It's done to help with anti-spam in general on the internet. A large percentage of PCs (especially windows PCs) are compromised and blocking outbound port 25 is a standard measure by ISPs to prevent those from being used as spambots. If you have a legitimate need for outbound port 25 traffic then most ISPs will unblock it for you on request (if you have a static IP, that is). That said, even if they do you will still likely be listed on a number of different policy blacklists which you will then have to play whackamole with to get your email accepted by other servers on the internet. A much better approach is to use a relayhost or to get a cheap VPS to relay through.

Comment Re:Most severs shouldn't be vulnerable (Score 2) 245

For one it can't be hijacked as easily as these ISPs are doing.

...which they're *not* doing. This article is a farce written by someone who can't even configure his email client to use the correct port for submission. He's trying to use port 25 which is only for MX to MX communication and not for submission, he should be using 587 and if he did there would very likely be no problems.

Comment Re:Most severs shouldn't be vulnerable (Score 5, Informative) 245

Look, most severs these days are configured in such a way that STARTTLS runs on a different port than the plain-text connection.

Wrong. STARTLS specifically allows for both plain text and TLS on the same port.

The server will reject login requests until the STARTTLS handshake is completed.

Partially correct. A well configured server will behave this way on the *submission* port (587) but if the MX port (25) were configured this way then you would be blocking a lot of legitimate email from old servers on the internet that do not support STARTTLS and as such is is not recommended to require STARTTLS for port 25 MX to MX communication. Also even when STARTTLS is used the connection is still plain text until STARTTLS is negotiated.

But take it from a guy who worked on an email client

Thanks for giving me a link to yet another piece of software written by someone who doesn't understand the technology behind it.

(Also: STOP USING STARTTLS!!!)

Wrong again. The only way to have an encrypted SMTP submission channel without STARTTLS (other than tunnelling through ssh or something like that) is via SMTPS (port 465). SMTPS is long ago deprecated and should not be used. Port 465 was *never* officially registered for this use and was essentially "hijacked" and there are only a very small number of old email clients that support SMTPS but do not support STARTTLS. You *should* be using STARTTLS over port 587 which is the submission port. Also STARTTLS is the only legitimate means of encryption between a submission server and an MX.

Of note (which I've also said elsewhere), the real reason the author of the original article had problems is because he is trying to use port 25 for submission. He should be using the submission port (587) and it is highly unlikely that his ISP would be blocking the STARTTLS flag on that port.

Comment Re:smtpd_tls_security_level=encrypt (Score 2) 245

Kind of, smtpd_* is for when postfix is the server and smtp_* is for when postfix is the client (ie when it connects to another server to relay mail). At any rate this setting should only be used for submission and not for server to server communication otherwise you will end up blocking mail to and from other servers that do not support TLS (there are many). The default setting for this is "may" which is for "opportunistic" TLS which can fall back to plain text if need be.

If you RTFA you will see that the author is trying to submit mail to port 25 on his email server which is supposed to be for MX to MX communication only. If he were to submit to the proper submission port (587) he would likely find that the STARTTLS flg is not blocked by his ISP, in other words this whole article is a farce written by someone who doesn't know what they're talking about.

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