Red Hat Postfix FAQ

Red Hat, Inc.

This document is meant to help new Postfix administrators with known problems, gotchas, and workarounds that can aid in getting the Postfix MTA installed and running on your Red Hat Linux system quickly and easily. We have attempted to document the most common issues and "gotchas" that arise. There is an important "sister document" to this FAQ, the Red Hat Postfix HOWTO.

Table of Contents

1. Introduction

2. Preface

3. Installation & Initial Configuration Issues

3.1 Where can I get RPMs for Postfix?
3.2 I downloaded the RPM, but it doesn't install. I get an error about failed dependencies.
3.3 Okay... it's installed. Now what do I do?
3.4 What happened to my aliases file?
3.5 I run majordomo and I had all of my aliases in /etc/mail/majordomo. What do I do now?
3.6 What mail delivery agent (MDA) does Postfix use?
3.7 How can I secure Postfix so it won't answer verify requests?
3.8 I have several virtual domains on my existing sendmail setup. How do I enable virtual hosting with Postfix?
3.9 With sendmail I would just -HUP sendmail or use the initscript to restart it after I'd made configuration changes. What's the equivalent to this with Postfix?
3.10 With sendmail I could manually flush the queue by issuing a sendmail -q command. What's the equivalent command for Postfix?
3.11 I need to use some map files equivalent to the access file or the mailertable with sendmail. How do I hash them to .db format?
3.12 How do I get Postfix to start up on boot like sendmail did?
3.13 How do I set the queue delay with Postfix?
3.14 How can I use Postfix from my dial-up machine at home?

4. Postfix Install Issues

4.1 I am using Postfix on Red Hat Linux 6.x. Recently there was an errata update for syslogd which I installed and all of a sudden qmgr has stopped logging. What's wrong?
4.2 I have recently installed Postfix at my ISP and when I start it up it will only run for an hour or so. I think we have too many users on it, (or something) because it spirals steadily down, ending up with no swap and no memory left. Is there a way that we could set a limit on the number of connections, or processes that Postfix can start?
4.3 I am a dial-up user and I've done everything right so far (I think). I can get my mail just fine with fetchmail and mail works locally as it should. The trouble is that my user name on my local account is not the same as my user name at my ISP so my mail goes no where when I send it. What can I do to fix this?
4.4 I'm running a series of restrictions to stop spam and I'm wondering how inbound mail is passed through these checks?
4.5 We are a medium sized investment house and we have some odd legal requirements for our e-mail. Everything sent by everyone has to be backed up locally as documentation for the SEC. Can this be done with Postfix?
4.6 I'm getting an error when I send mail to my own server. It says "mail for mydomain.com loops back to itself". What do I do to fix this?
4.7 When I set up $mynetworks in /etc/postfix/main.cf I used CIDR shorthand (e.g. 127/8). I now appear to be having a problem. I guess Postfix doesn't like shorthand CIDR entries?
4.8 I've got some bounced mail in the queue which is not being accepted by the remote site. How can I remove it from the queue?
4.9 I got a really weird error on startup. It looks like this: “Nov 23 02:10:59 myhost postfix/local[20449]: fatal: unsupported dictionary type: dbm”, what's the problem?
4.10 Is there a good log analysis tool for Postfix?
4.11 Is there an active mailing list for Postfix?

5. Additional Questions?

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		Introduction