no authentication for incoming mail on sendmail, linux (debian) [closed]

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.

---

This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.

Closed 8 years ago.

Improve this question

I have installed sendmail on my webserver. Sending and receiving emails does work, but when I use authentication on port 25 ( to avoid spam attacks), I can't receive emails anymore. All I get is an authentication error.

Is there a way to deactivate authentication in sendmail for incoming mail?

Edit 1 : In my sendmail configuration I have this lines:

DAEMON_OPTIONS(Name=ESMTP,Port=465,Modifiers=a')
DAEMON_OPTIONS(Name=STARTTLS,Port=587,Modifiers=a') 
DAEMON_OPTIONS(`Name=SMTP,Modifiers=a') 

Answer 1

You can not force authentication on port SMTP (25) if you want to receive messages from "strangers" (other SMTP hosts worldwide).

You should require authentication on SMTPS (465) and MSA (587) ports.

You may reject connection from DUL (dynamically allocated) IP addresses for unauthenticated connections and addresses listed by other DNSBL lists. Use FEATURE(enhdnsbl,...) with some DNSBL listing DUL ranges and FEATURE(delay_checks,...).

---

BTW You have missed s Modifier for SMTPS.

DAEMON_OPTIONS(`Name=SMTPS,Port=465,Modifiers=sa')