:-)

On 3/3/21 5:18 PM, Bill Cole wrote:
On 3 Mar 2021, at 9:51, Marek Kozlowski wrote:
:-)
When testing my server via telnet ... 25 it works:

MAIL FROM: <"">
250 2.1.0 Ok

Rejections in SMTP based on client, helo, and sender policy criteria are normally postponed until the RCPT stage of the transaction, no matter what the reason for rejection. A '250' response to MAIL only indicates that the command was issued in the correct state (after EHLO or HELO) and was not syntactically invalid.

Obviously. Sorry for a stupid question. Sleeping for more than 2h/day has a great future.

Moreover an active 'reject_sender_login_mismatch' restriction not blocked mail from SASL authenticated user (a compromised account) with such an envelope address. What have I missed?

Log entries showing actual mail being allowed with such a sender along with the output of 'postconf -n' would be necessary to understand precisely why it was not rejected.

In short I believe it must be somewhere here:


smtpd_sender_login_maps = ldap:/etc/postfix/ldap.cf
----------------------------------------------------
server_host = ldaps://<sth>:636
version = 3
search_base = <sth>
query_filter = (&(mail=%s)(<sth>))
result_attribute = cn
result_format = %s
bind = no
dereference = 3

main.cf:
smtpd_sender_restrictions =
        <sth>
        reject_sender_login_mismatch,
        reject_non_fqdn_sender,
        permit

One user's password has been compromised. Someone had authenticated as this user (SASL) and was able to send mail with:

Return-Path: <>

I'm afraid logs were not as detailed as needed. I'm trying to understand: how??

BTW:

MAIL FROM: <>
503 5.5.1 Error: nested MAIL command
MAIL FROM: ""
503 5.5.1 Error: nested MAIL command

Those are precisely what they say: SMTP does not allow more than one MAIL command per transaction. Once you've had a successful MAIL command, you must either complete the transaction OR send a RSET command before Postfix will consider any new MAIL command.

Obviously. Sorry for a stupid question. Sleeping for more than 2h/day has a great future.

Best regards,
Marek


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