email server: Postfix real-time centralized whitelisting

I am using Postfix & # 39; s postscreen filters and I have a couple of static CIDRs whitelisted using the postscreen_access_list characteristic. However, what I find when testing this feature is that when sending mail to my servers using a large mail server, it is that after the initial and expected attempt …

NOQUEUE: reject: RCPT from (###.###.###.###):#####: 450 4.3.2 Service currently unavailable;
PASS NEW (###.###.###.###):#####

… the next time the attempt is made (which is supposed to be made because it has been automatically whitelisted), most of the time it's from a totally different IP, because your outgoing servers are part of a farm. This causes some emails to be delayed more than an hour, if not longer.

I understand this is by design, but in our scenario, I am going to have MANY client servers hitting this lag, so I am wondering if there is a way to create a centralized white list, that all of our client servers get updated and validate against on instead of keeping yours?

smtp – Postfix via relay server and LMTP configuration for inbound delivery to local mailboxes

I am trying to configure something like below setting for local delivery (to force local delivery through relay server):

Dovecot -----------> Postfix --> Relay Server -┐
Dovecot <-- LMTP <-- Postfix <-----------------┘

I have already configured the top of it. I can send an email from the IMAP mailbox through Postfix to the relay server, but then the server will send it back to the same Postfix, which will start sending that message back to a relay server to send back to the recipient's dovecot mailbox.

Any advice on how to configure Postfix or LMTP for such email route?

I was trying to follow examples from here and from here

algorithms: why is postfix used more often than the prefix expression?

I was reading stack and came across the infix, preifx, and postfix expression, so I understood why postfix / prefix expressions are preferable to infix expressions (due to their unequivocal nature). But I don't get enough information about the popularity ratio of the postifx expression over the prefix expression.

Why aren't we using the prefix expression more than the postfix expression more often?

I suppose that ,

  1. is related to the ease of converting the infix to postfix
  2. or the postifx evacuation process is easier than the prefix.

If so, please have someone explain it.

Thank you.

smtp: BDAT mail command in Postfix

I have been trying to investigate the BDAT command, specifically regarding Postfix. I couldn't find a lot of information and I have 3 questions.

(1) As far as I can tell, Postfix is ​​BDAT compatible since version 3.4.

When I test it on some Postfix instances (eg 3.4.6) I get the following:

$ telnet localhost 25
Trying ::1...
telnet: connect to address ::1: Connection refused
Connected to localhost.
Escape character is '^)'.
220 xxx ESMTP Postfix
250 xxx
250 2.1.0 Ok
250 2.1.5 Ok
BDAT 100
502 5.5.2 Error: command not recognized

$ postconf mail_version
mail_version = 3.4.6

can someone tell me why? It is not disabled according to the instructions in the documentation.

(2) What does the following mean in mail records? (bdat = x)?

postfix/smtpd(81026): disconnect from xxx( ehlo=2 starttls=1 mail=1 rcpt=1 **bdat=2** quit=1 commands=8
postfix/smtpd(86493): disconnect from xxx( ehlo=2 starttls=1 mail=1 rcpt=1 **bdat=1** quit=1 commands=7

Cannot receive postfix, dovecot + spamassassin emails

I have been trying to install postfix, dovecot and spamassassin setup.
But I got caught up in this problem. Sending mail is possible, but receiving email
is what doesn't work I will receive an "Undelivered Mail Returned to Sender" email when I try.
the error in this email is

: user unknown. Command output:
    net_connect_unix(/var/run/dovecot/stats-writer) failed: Permission denied

I already tried putting this in my dovecot.conf

service stats {
  unix_listener stats-writer {
    user = mail dovecot postfix debian-spamd **tried it all!**
    group = mail dovecot postfix debian-spamd **tried it all!**
    mode = 0660



My dovecot.conf:


My mail.log:

My syslog:

dovecot – How do I set my email name in postfix?

Environment: CentOS, Postfix and Dovecot.

Question: How do I set my email name in Postfix?

Example: could be the email address but the name would be "The President".

When I open vmailbox I don't see a place to add a name.
/etc/postfix/vmailbox     email/

The name that appears in gmail in front of the subject is automatically "tested".

Where can I add a name?

linux – Postfix – Verification of origin of multiple recipients

I have successfully configured Postfix in Ubuntu 18.04 using relay_recipient_maps through two different methods, but I can only use one method in the config file.

The first method is to use LDAP queries to our AD servers for each email to verify if the address exists.
LDAP method:
relay_recipient_maps = ldap: /etc/postfix/

I also have a script to generate a file every X minutes from valid email addresses.
relay_recipient_maps = hash: / etc / postfix / relay_recipients

What I'd like to do is use LDAP as the primary method and use the file as a secondary check only if LDAP can't find the address.

it's possible?

Thanks in advance.

Postfix relay server: server error

There are two instances of aws A and B.

A is configured as a mail server following this article:
It is working fine, and now if someone sends an email to it is received through A and can be seen from anywhere through /squirrelmail.

Now, I need to configure B as a relay server so that all emails arrive first at B and then B send them to A.

I have been reading many articles like:
All these items create a sasl_passwd file containing the username and password.
Is there a way to do this without creating this file in plain text or hashing?

Another query is: Is the term relay server correct for what I'm trying to do?

email – Postfix maildrop -> pickup "from:" verification

I was surprised to note that sending email from the local server account allows any user to send messages with:

From: whatever @ whateverdomain

This is a security problem, since it allows identity theft.

When sending emails from the local server account, the emails are placed in the maildrop directory and the Postfix daemon collection sends the email.

Searching the Postfix documentation (man pickup) does not show a dedicated verification for this problem.

How can you resolve that, without disabling the Pickup Service, the system is required to function properly?

Email: Postfix stops specific users to send emails with attachments outside their dome

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