The qmail Handbook

501 Pages·2002·6.288 MB·English

by  Dave Sill (auth.)

The qmail
Handbook
DAVE SILL
Apress'·
The qmail Handbook
Copyright ©2002 by Dave Sill
Originally published by Apress in 2002.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by
any means, electronic or mechanical. including photocopying, recording, or by any information
storage or retrieval system, without the prior written permission of the copyright owner and
the publisher.
ISBN 978-1-893115-40-8 ISBN 978-1-4302-1134-1 (eBook)
DOI 10.1007/978-1-4302-1134-1
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Far my mather
Brief Contents
Acknowledgments .....................................................x ii
About the Author ....................................................x v
About the Technical Reviewer .....................................x vii
Introduction ....................................................... .x ix
Chapter 1: Introducing qmail ....................................... 1
Chapter 2: Installing qmail .......................................2 7
Chapter 3: Configuring qmail: The Basics ......................... 93
Chapter 4: Using qmail ............................................ 121
Chapter 5: Managing qmail ........................................ 159
Chapter 6: Troubleshooting qmail ................................ 199
Chapter 7: Configuring qmail: Advanced Options ...............2 25
Chapter 8: Controlling Junk Mail ................................2 85
Chapter 9: Managing Mailing Lists ...............................2 95
Chapter 10: Serving Mailboxes .................................... 327
Chapter 11: Hosting Virtual Domain and Users .................. 375
Chapter 12: Understanding Advanced Topics ..................... 391
Appendix A: How qmail Works ...................................... 417
Appendix B: Related Packages ..................................... 431
Appendix C: How Internet Mail Works ............................ 443
Appendix D: qmail Features ...................................... .449
Appendix E: Error Messages ...................................... .457
Appendix F: Gotchas .............................................. .465
v
Contents
Acknowledgments ................................................x iii
About the Author ................................................x v
About the Technical Reviewer .............................x vii
Introduction .....................................................x ix
Chapter 1: Introducing qmail ............................... 1
Overview ...............................................................2
What 1s qmail? .......................................................2
Why Use qmail? .......................................................3
Why Not Use qmail? ................................................... 9
qmail Features ...................................................... 12
History ............................................................... 15
Architecture ......................................................... 16
License ............................................................... 19
Documentation ........................................................2 0
Support ...............................................................2 3
Conclusion ...........................................................2 5
Chapter 2: Installing qmail ...............................2 7
Overview .............................................................2 7
Preparing to 1nstall qmail ........................................2 8
1nstalling qmail: Quick-Start 1nstructions .....................3 8
1nstalling qmail Step by Step .....................................5 2
An Overview of the Finished Product ..............................8 6
1nstalling from RPMs ............................................... 87
Conclusion ........................................................... 91
vii
Chapter 3: Configuring qmail: The Basics ..............
93
Overview ............................................................. 93
Control Files Reference ............................................ 93
Relaying ........................................................... .1 10
Multiple Host Names ............................................... 115
Virtual Domains .................................................... 115
Aliases .............................................................. 116
The qmail-users Mechanism ........................................ 117
Conclusion .......................................................... 119
Chapter 4: Using qmail ......................................
121
Overview ............................................................ 121
Sending Messages ................................................... 121
Receiving Messages ................................................. 136
User Utilities ..................................................... 148
Conclusion .......................................................... 156
Chapter 5: Managing qmail .................................
159
Overview ............................................................ 159
Understanding the qmailctl Script ............................... 159
Learning qmail' s Management Commands ........................... 165
Managing the Queue ................................................. 187
Conclusion .......................................................... 198
Chapter 6: Troubleshooting qmail .......................
199
Overview ............................................................ 199
Process Monitoring ................................................ .2 00
Understanding Logs ................................................ .201
Using Message Headers .............................................2 11
Testing ..............................................................2 17
Fixing Common Problems ............................................2 18
Conclusion ..........................................................2 23
viii
Chapter 7: Configuring qmail: Advanced Options ...
225
Overview ............................................................2 25
Setting Up Typical Configurations ...............................2 26
Migrating from Sendmail to qmail ................................2 37
Modifying the Source Code ........................................2 49
Using Quick Mail Transfer Protocol ..............................2 54
Using Quick Mail Queuing Protocol ...............................2 58
Securing SMTP .......................................................2 64
Performance Tuning .................................................2 73
Conclusion ..........................................................2 84
Chapter 8: Controlling Junk Mail .......................
285
Overview ............................................................2 86
An Ounce of Prevention .............................................2 86
Setting System-Level Controls ....................................2 87
Setting User-Level Controls ......................................2 92
Conclusion ..........................................................2 94
Chapter 9: Managing Mailing Lists ......................
295
Overview ............................................................2 95
Setting Up Simple Mailing Lists .................................2 95
Working with ezmlm .................................................2 97
Working with Majordomo ............................................3 05
Working with Mailman .............................................. 315
Using Other MLMs ................................................... 324
Conclusion .......................................................... 326
Chapter 10: Serving Mailboxes ........................... 327
Overview ............................................................ 328
Installing and Using POP3 Servers ............................... 328
Installing and Using IMAP Servers ............................... 344
Securing POP3 ....................................................... 353
Securing IMAP ....................................................... 362
Retrieving Mail with POP3 and IMAP .............................. 369
Conclusion .......................................................... 374
ix
Chapter 11: Hosting Virtual Domain and Users ...... 375
Overview ............................................................ 376
Choosing between VMailMgr and Vpopmail ........................ .376
Using VMailMgr ..................................................... 377
Using Vpopmail ..................................................... 383
Conclusion .......................................................... 389
Chapter 12: Understanding Advanced Topics .......... 391
Overview ............................................................ 391
Single-Recipient Delivery vs.
Multiple-Recipient Delivery .................................. 391
Using Variable Envelope Return Paths ........................... 394
Configuring Scalable Servers ..................................... 395
Using Lightweight Directory Access Protocol .................. .401
Using Structured Query Language ................................ .402
Virus Scanning .....................................................4 03
Conclusion ......................................................... .414
Appendix A: How qmail Works .............................
.417
High-Level Overview ............................................... 417
Receiving Modules ................................................. .418
Sending Modules .................................................... 425
Appendix B: Related Packages ............................
.431
checkpassword ...................................................... .431
Courier-IMAP ........................................................ 432
daemontools ......................................................... 432
djbdns .............................................................. .432
dot-forward ......................................................... 433
ezmlm ................................................................ 433
ezmlm-idx ........................................................... 433
fastforward ......................................................... 434
getmail ............................................................. .434
maildrop ............................................................ 434
mess822 ............................................................. .435
x
oMail-webmail ...................................................... .435
oSpam ............................................................... .435
qlogtools .......................................................... .436
qmail-autoresponder .............................................. .436
qmail-qfilter ...................................................... .436
Qmail-Scanner ...................................................... .437
qmail-vacation .................................................... .437
qmailanalog ........................................................ .437
safecat .............................................................. 439
serialmail ......................................................... .439
SqWebMa il .......................................................... .440
syncdir ..............................................................4 40
TMDA ................................................................ .440
ucspi-tcp .......................................................... .441
VMailMgr ............................................................ 441
Vpopmail ............................................................ 441
Appendix C: How Internet Mail Works ..................
.443
How a Message Gets from Point A to Point B ................... .443
Envelopes vs. Headers ............................................ .444
Finding More Information ......................................... 446
Appendix D: qmail Features ................................
449
Setup Features .................................................... .449
Security Features ................................................. .449
Message Construction ............................................. .450
SMTP Service ....................................................... .450
Queue Management .................................................. .451
Bounces .............................................................. 452
Routing by Domain ................................................. .453
SMTP Delivery ...................................................... .453
Forwarding and Mailing Lists ..................................... 454
Local Delivery .................................................... .454
POP3 Service ....................................................... .455
xi