At work i setup a programming environment for developers. The server is on a natted IP address range and could not send email to our internal mail server because of some weird firewall issues.

All email going to external sites was working fine but to send to our internal domain it wouldn’t work so i had to figure out how to get emails out. I am running postfix on the server so what I did i had postfix relay the mail to my ISP’s mail server. I had done this in the past using sendmail but with postfix I had to do the following.

Continua”Configure Postfix with smart host”

This is a quick document on how to get yourself out of some binds I’ve run into with sendmail. These aren’t going to be the most organized, but I figure someone else may find these useful.

Continua”Rings of Saturn Sendmail Tips”

Sending Email to invalid addresses Adventure.

So last night our company sent an invite to people to download some PDF file
the email went out to over 4,000 people. Our php application tried to send
the messages but the messages were not going out 3 hours later the mail server
was clogged with 3,000 messages that were still sitting on the queue.

Continua”Fixing sendmail Queue”

HOW I UPGRADED MY IMAP SERVER ON PENGUINCARES

So my email server was running an RPM that provided imap service but it was slow.

I figured i can speed up my server if I install a new imap server, I decided to go
with dovecot server so I removed the old rpm file

Release : 10 Build Date: Wed 17 Apr 2002 06:44:15 PM EDT
Install date: Tue 07 Jun 2005 10:57:45 PM EDT Build Host: stripples.devel.redhat.com
Group : System Environment/Daemons Source RPM: imap-2001a-10.src.rpm
Size : 2303900 License: University of Washington Free-Fork License
Packager : Red Hat, Inc.
URL : http://www.washington.edu/imap/
Summary : Server daemons for IMAP and POP network mail protocols.
Description :
The imap package provides server daemons for both the IMAP (Internet
Message Access Protocol) and POP (Post Office Protocol) mail access
protocols. The POP protocol uses a “post office” machine to collect
mail for users and allows users to download their mail to their local
machine for reading. The IMAP protocol allows a user to read mail on a
remote machine without downloading it to their local machine.

Continua”HOW I UPGRADED MY IMAP SERVER ON PENGUINCARES DOVECOT”

Installing Mailscanner ClamAv and Spamassassin

---

Intro

In this article we will see how to install a basic system to avoid your system to spread spam, virus and any type of crap to your users.

Since it is what we use, the machine which we are speaking about is a CentOS 4.0 with BlueQuartz control panel, to be honest, the one provided by Nuonce.net.

Continua”MailScanner with Sendmail setup”

Using SMTP AUTH and STARTTLS with sendmail

A quick start guide for Red Hat/Fedora Linux

SMTP AUTH allows users to relay mail after successfully
authenticating. This has augmented and even replaced IP address-based access
controls, mainly due to the wide adoption of dynamically allocated IP addresses
and the demands of roaming users. It makes more sense to control relaying at
the user level, regardless of the host or its location on the Internet, but
care must be taken to protect passwords from being sent in the clear.

Although support is maturing, implementation can still be complex. This
guide will help you to configure sendmail to use SMTP AUTH with STARTTLS on Red
Hat/Fedora Linux. Much of the information presented here will also be useful on
other platforms.

Continua”Using SMTP AUTH and STARTTLS with Sendmail”

Index DNSBL: Configuring Sendmail for DNS-Based Blacklisting Modified: 12 Feb 2007

——————————————————————————–

DNSBL: Configuring Sendmail for DNS-Based Blacklisting
By Weldon Whipple

——————————————————————————–

Contents
Introduction
Step 1: Choose Which Blacklist(s) to Use
Step 2: Modify sendmail.cf for Blacklisting
Optional: Enable DNSBL for Designated Users Only
Alternate Disabling Option: Exempt Specified Local Users from Blacklisting
Optional: Customize the Error Message
Optional: Change Default Behavior When Lookups Fail Temporarily
Appendices
Appendix A: Notes on Creating Your Own DNS Blacklist
Appendix B: Enhanced DNS BlackLists
Appendix C: Subscriber-Only Blacklists–mail-abuse.org
Appendix D: Name Server Issues
Afterword
Introduction
These instructions describe how to modify sendmail’s configuration file to enable the dnsbl (DNS Blacklist) feature to block incoming e-mail from IP addresses that are listed on one or more blacklists. These particular blacklists are checked by sendmail during the SMTP conversation, avoiding the generation of the bounce messages that are generated (for example) when SpamAssassin–called from procmail–consults DNS Blacklists. (The configuration of SpamAssassin to consult DNS Blacklists is outside the scope of this document.)

Here is how DNSBLs work:

Continua”DNSBL: Configuring Sendmail for DNS-Based Blacklisting”

What is an RBL list?

An RBL style list is a basicly a DNS server that maintains a list of known spam rlays.
It is used by sendmail (or another MTA) when mail is recived. The MTA will make a standard
DNS query to the list server of your choice and reject the incoming mail if the server it

originated from is listed in the RBL server. This will cause incoming spam to be rejected
without even having the message come to your server and waste your bandwidth.

Continua”Enable RBL lists on Sendmail”

with thanks to Craig Outcalt for
pointing out the original
"http://www.backwatcher.org/writing/howtos/obsd-sendmail+sasl.html">OpenBSD
Sendmail + SMTP AUTH Mini-HOWTO [ "backwatcher.html">local]

This howto will detail how to (durh) set up the version of sendmail included
with OpenBSD 3.3 to accept authentication via Cyrus SASL.

these instructions work just fine with 3.6, and you do NOT need to re-compile
sendmail to enable SSMTP.
Continua”OpenBSD Sendmail + SMTP AUTH Mini-HOWTO [local]“

Cool interactive sendmail troubleshooting.

if you want to view all the behind the curtains work done by sendmail
while trying to send an email you can try the following.

sendmail -v emailaddress@domain.com < file_you_wanna_send

here is am sending an email to imrobotmaker"@"yahoo.com

Continua”Sendmail flags for troubleshooting + PHP mail()”