Smarthost With SMTP Authentication For Sendmail

First we have to create the authentication information

cd /etc/mail
mkdir auth
chmod 700 auth
cd auth
vi client-info

Enter the following, substituting the desired mail server, username and password

AuthInfo:mail.server.com "U:username" "P:password"

Now we create the hash

makemap hash client-info < client-info
chmod 600 client-info*
cd /etc/mail
vi sendmail.mc

Now we tell sendmail to smarthost and use our authentication hash, substituting the desired mail server

define(`SMART_HOST',`mail.server.com')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
FEATURE(`authinfo',`hash /etc/mail/auth/client-info')dnl

Find the existing line for smarthost and replace it with those three lines.

Lastly, rebuild the config and restart sendmail

m4 sendmail.mc > sendmail.cf
service sendmail restart

DKIM Key 1024 2048 Bits Causes BIND NAMED Error

By default BIND can only handle 255 characters per line for record length, however it can handle values up to 65,536 characters.

The trick to getting a DKIM key (or any zone record for that matter) to wrap within this limit you do the following:

_domainKey.domain.com. IN  TXT ( "p=part of your key"
                                  "another part of your key"
                                  "last part of your key" )

By wrapping the entire value in brackets we keep it tied to one record and by quoting each line individually it allows us to surpass the line limit.

Common errors with this:

dns_rdata_fromtext: near eol: unbalanced quotes
dns_master_load: label too long
dns_master_load: syntax error
zone: loading master file: ran out of space

Find All Catch-All Emails On DirectAdmin

find /etc/virtual -name "aliases" -exec grep -H "*: " {} \; | grep -v "fail" | grep -v "blackhole"

Delete All E-Mail Messages To A Specific Recipient In Exim

exiqgrep -r [email_adderss_here] | exiqgrep -i | xargs exim -Mrm

Block Outbound Port 25 SMTP For Untrusted Users With IPtables

This will only allow port 25 access to users: mail, mailman and root

iptables -A OUTPUT -d 127.0.0.1 -p tcp -m tcp --dport 25 -j ACCEPT
iptables -A OUTPUT -p tcp -m tcp --dport 25 -m owner --gid-owner mail -j ACCEPT
iptables -A OUTPUT -p tcp -m tcp --dport 25 -m owner --gid-owner mailman -j ACCEPT
iptables -A OUTPUT -p tcp -m tcp --dport 25 -m owner --uid-owner root -j ACCEPT
iptables -A OUTPUT -p tcp -m tcp --dport 25 -j REJECT --reject-with icmp-port-unreachable

Enable SPF On All cPanel Accounts

for i in `ls /var/cpanel/users/`;do /usr/local/cpanel/bin/spf_installer $i ;done

Enable DKIM On All cPanel Accounts

for i in `ls /var/cpanel/users` ;do /usr/local/cpanel/bin/dkim_keys_install $i ;done

Delete All Messages In Qmail Spool With Plesk

/usr/local/psa/admin/bin/mailqueuemng -D

This works (at the very least) on Plesk 9.5.x

Sending Email From A Bash Script

#!/bin/bash
CONTENT="This is the content"
SUBJECT="This is the subject"
TO_ADDRESS=destination_email_address_here
FROM_ADDRESS=source_email_address_here

echo $CONTENT | mail -s $SUBJECT $TO_ADDRESS -- -r $FROM_ADDRESS

Note:
The -- delimits that the options following it are piped to sendmail

Enable All Services For A Domain Using Vpopmail

domain=$1
vpmdir=/home/vpopmail
acctlist=$(find $vpmdir/domains/$domain -mindepth 1 -maxdepth 1 -type d) for acctpath in $acctlist; 
do
     account=${acctpath##*/}
     address=$account@$domain
     echo "changing $address"
     $vpmdir/bin/vmoduser -x $address
done 

Usage ./[the_above_script]/[domain]

Disable All Services For A Domain Using Vpopmail

domain=$1
vpmdir=/home/vpopmail
acctlist=$(find $vpmdir/domains/$domain -mindepth 1 -maxdepth 1 -type d) for acctpath in $acctlist; 
do     
     account=${acctpath##*/}
     address=$account@$domain
     echo "changing $address"
     $vpmdir/bin/vmoduser -p -s -w -i -r $address
done 

Usage ./[the_above_script]/[domain]

Sending E-Mail As An Authenticated User Using Telnet

The first thing you have to do is generate your AUTH PLAIN token from the command line (assuming Linux):

perl -MMIME::Base64 -e 'print encode_base64("\000your-user\@your-domain.com\000your-password");' 

Now telnet to your mail server:

telnet mail.your-domain.com
Trying 1.2.3.4...
Connected to mail.your-domain.com.
Escape character is '^]'.
220 mail.your-domain.com ESMTP

Now we need to say Hi:

ehlo my-current-hostname.com

And we'll receive the list of supported commands:

220 mail.your-domain.com ESMTP
250-mail.your-domain.com
250-STARTTLS
250-PIPELINING
250-8BITMIME
250-SIZE 0
250 AUTH LOGIN PLAIN CRAM-MD5

We want to AUTH PLAIN using the token we created:

AUTH PLAIN [token here]

If your login credentials are accepted you'll receive:

235 ok, go ahead (#2.0.0)

Now you can send a message (I've included the numeric response codes below each command, you wouldn't enter those):

MAIL FROM: your-user@your-domain.com
250 ok
RCPT TO: another-user@another-domain.com
250 ok
DATA
354 go ahead
To: another-user@another-domain.com
From: your-user@your-domain.com
Subject: This Is How To Send An Authenticated Email Via Telnet 
Date: Mon, 21 May 2012 12:00:00 -0500
Testing auth plain via telnet.
To end the message well place a period on it's own line and then hit enter.
.
250 ok
QUIT

And there you have it!

Track And Log Formmail SPAM In cPanel

First step is to move the sendmail binary

mv /usr/sbin/sendmail /usr/sbin/sendmail.act

Create a "new" sendmail binary

vi /usr/sbin/sendmail

...and add:

#!/usr/bin/perl

# use strict;
use Env;
my $date = `date`;
chomp $date;
open (INFO, ">>/var/log/formmail.log") || die "Failed to open file ::$!";
my $uid = $>;
my @info = getpwuid($uid);
if($REMOTE_ADDR) {
print INFO "$date - $REMOTE_ADDR ran $SCRIPT_NAME at $SERVER_NAME \n";
}
else {

print INFO "$date - $PWD - @info\n";

}
my $mailprog = '/usr/sbin/sendmail.act';
foreach (@ARGV) {
$arg="$arg" . " $_";
}

open (MAIL,"|$mailprog $arg") || die "cannot open $mailprog: $!\n";
while (<stdin> ) {
print MAIL;
}
close (INFO);
close (MAIL);

Lastly:

chmod +x /usr/sbin/sendmail
echo > /var/log/formmail.log
chmod 777 /var/log/formmail.log