book

qmail

Name: qmail
Author: John Levine
ISBN: 9781565926288

by John Levine

March 2004

Intermediate to advanced

248 pages

7h 18m

English

O'Reilly Media, Inc.

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Preface
What’s Inside?Part I: Introduction to QmailPart II: Advanced QmailStyle ConventionsExamples and PatchesComments and QuestionsAcknowledgments
I. Introduction to Qmail
1. Internet Email
1.1. Mail Basics1.1.1. Addresses1.1.2. Envelopes1.1.3. Messages1.1.4. Lines1.2. Mailstore1.2.1. Transparent Mailstore1.2.2. Opaque Mailstore1.2.2.1. POP31.2.2.2. IMAP41.3. The Structure of Internet Mail
2. How Qmail Works
2.1. Small Programs Work Together2.1.1. Each Program Does One Thing2.1.2. The Principle of Least Privilege2.1.3. Program Wrapping2.1.4. No New Languages2.1.5. Configuration Files2.2. What Does a Mail Transfer Agent (MTA) Do?2.3. The Pieces of Qmail2.3.1. A Message’s Path Through Qmail
3. Installing Qmail
3.1. Where to Find Qmail3.1.1. Copyright3.1.2. Should I Upgrade?3.1.3. Other Software You Should Fetch3.2. Creating the Users and Groups3.2.1. The adduser Script3.2.2. Adding by Hand3.2.3. Nofiles Group Really Has No Files3.3. Configuring and Making the Software3.3.1. conf-break3.3.2. conf-cc3.3.3. conf-groups3.3.4. conf-ld3.3.5. conf-patrn3.3.6. conf-qmail3.3.7. conf-spawn3.3.8. conf-split3.3.9. conf-users3.3.10. Build Using make3.3.11. If the Build Fails3.3.12. Building the Other Packages3.3.13. Installing Qmail3.3.14. Installing Other Programs3.4. Patching Qmail
4. Getting Comfortable with Qmail
4.1. Mailboxes, Local Delivery, and Logging4.1.1. Mailbox Format4.1.2. Local Delivery4.1.3. Logging4.2. An Excursion into Daemon Management4.2.1. Starting a Daemon4.3. Setting Up the Qmail Configuration Files4.4. Starting and Stopping Qmail4.4.1. Choosing a Startup File4.4.2. Fire `er Up4.4.3. Stopping Qmail4.5. Incoming Mail4.5.1. Configuration Files4.5.2. Setting Up the Daemons4.5.3. Make Some Mail Aliases4.5.4. Relaying for Local Users4.6. Procmail and Qmail4.7. Creating Addresses and Mailboxes4.8. Reading Your Mail4.9. Configuring Qmail’s Control Files4.10. Using ~alias4.11. fastforward and /etc/aliases4.11.1. Installing fastforward4.11.2. Using fastforward4.11.3. Alias File Format
5. Moving from Sendmail to Qmail
5.1. Running Sendmail and Qmail in Parallel5.1.1. Sendmail Switching Systems5.2. User Issues5.2.1. Mailbox Format and Location5.2.2. Qmail and .forward Files5.3. System Issues5.3.1. Deconstructing sendmail.cf5.3.2. Local Deliveries5.3.3. Hostnames and Masquerading5.3.4. Local and Virtual Domains5.3.5. Remote Domains, and Primary and Backup MXes5.3.6. Smarthosts5.3.7. Uucp and Other Specialized Deliveries5.3.8. Spam Filtering5.4. Converting Your Aliases File5.4.1. Address Forwarding5.4.2. Mailing Lists5.4.3. Program Deliveries5.5. Trusted Users
6. Handling Locally Generated Mail
6.1. qmail-queue6.1.1. Passing Input to qmail-queue6.1.2. Other Queueing Programs6.1.3. Wrapping qmail-queue6.2. Cleaning Up Injected Mail6.2.1. Accepting and Cleaning Up Locally Injected Mail6.2.1.1. Setting the envelope addresses6.2.1.2. Header rewriting6.2.1.3. Address rewriting6.2.2. Passing in Large Numbers of Addresses6.3. Accepting Local Mail from Other Hosts6.4. Distinguishing Injected from Relayed Mail
7. Accepting Mail from Other Hosts
7.1. Accepting Incoming SMTP Mail7.2. Accepting and Cleaning Up Local Mail Using the Regular SMTP Daemon7.2.1. Using Separate Relay and Injection Daemons7.2.2. Deciding On the Fly Which Daemon to Use7.3. Dealing with Roaming Users7.4. SMTP Authorization and TLS Security7.4.1. Installing and Building SMTP AUTH and (Optionally) TLS7.5. POP-before-SMTP7.5.1. Adding POP-before-SMTP to the POP Server7.5.2. Adding POP-Before-SMTP to the SMTP Server7.5.3. Using POP-before-SMTP with ofmipd7.5.4. Other POP-before-SMTP Daemons
8. Delivering and Routing Local Mail
8.1. Mail to Local Login Users8.1.1. Local Delivery .qmail Files and Default Delivery Rules8.1.2. Maildirs and Mail Clients8.2. Mail Sorting8.2.1. Mail Sorting with Subaddresses8.2.2. Mail Sorting with Filter Programs8.2.2.1. Mail sorting with procmail8.2.2.2. Mail sorting with maildrop8.2.3. More Mail Sorting

9. Filtering and Rejecting Spam and Viruses
9.1. Filtering Criteria9.2. Places to Filter9.3. Spam Filtering and Virus Filtering9.4. Connection-Time Filtering Tools9.4.1. Using Local Filtering Rules9.4.2. Using DNSBLs and DNSWLs9.5. SMTP-Time Filtering Tools9.5.1. Filtering in the SMTP Daemon9.5.2. Separate Filters Called from the SMTP Daemon9.5.2.1. Filtering with qmail-qfilter9.5.2.2. Filtering with qmail-scanner9.6. Delivery Time Filtering Rules9.7. Combination Filtering Schemes
II. Advanced Qmail
10. Local Mail Delivery
10.1. How Qmail Delivers Local Mail10.1.1. Identifying the User10.1.2. Locating the .qmail File10.1.3. Processing the .qmail File10.1.4. Defensive Features in qmail-local10.2. Mailbox Deliveries10.3. Program Deliveries10.3.1. Delivery Utilities10.3.1.1. forward10.3.1.2. bouncesaying10.3.1.3. condredirect10.3.1.4. except10.4. Subaddresses10.5. Special Forwarding Features for Mailing Lists10.6. The Users Database10.7. Bounce Handling10.7.1. Single Bounces10.7.2. Double Bounces10.7.3. Triple Bounces
11. Remote Mail Delivery
11.1. Telling Local from Remote Mail11.2. qmail-remote11.3. Locating the Remote Mail Host11.3.1. The smtproutes File for Outbound Mail11.3.2. Secondary MX Servers for Inbound Mail11.3.3. TCP Time-Outs11.4. Remote Mail Failures11.5. Serialmail11.5.1. Using Serialmail
12. Virtual Domains
12.1. How Virtual Domains Work12.2. Some Common Virtual Domain Setups12.2.1. Mapping a Few Addresses with .qmail Files12.2.2. Mapping Many Addresses with fastforward12.2.3. Per-User Subdomains12.2.4. Service Gateways12.2.4.1. Gateway design12.2.4.2. Gateway addressing12.2.4.3. Per-message service gateways12.2.4.4. Batched service gateways12.2.5. Mapping Individual Addresses12.2.6. POP Toasters12.3. Some Virtual Domain Details12.3.1. qmail-foo Versus qmail-alias-foo12.3.2. Local-Only Domains
13. POP and IMAP Servers and POP Toasters
13.1. Each Program Does One Thing13.1.1. The Flow of Control13.1.2. Functional Partitioning13.1.2.1. Flexibility13.1.2.2. Testability13.2. Starting the Pop Server13.2.1. Prerequisite Packages13.2.2. Directories13.2.3. The Listening Script13.2.4. The Logging Script13.2.5. tcpserver Rules13.2.6. Putting It All Together13.3. Testing Your POP Server13.3.1. You Cannot Connect to the POP Server13.3.2. You Can Connect, but Then Something Fails13.4. Building POP Toasters13.4.1. Installing Vpopmail13.4.2. Setting Up Vpopmail13.4.2.1. Creating virtual domains13.4.2.2. Creating mailboxes13.4.2.3. Starting the POP service13.4.2.4. Roaming users13.4.3. Some Handy Vpopmail Tricks13.4.3.1. Handling unknown users13.4.3.2. Forwarding a user’s mail and other per-user special handling13.4.3.3. Enforcing mail quotas13.4.3.4. Mail bulletins13.4.3.5. Storing user data in a database13.4.3.6. Data replication and other MySQL tricks13.5. Picking Up Mail with IMAP and Web Mail13.5.1. Courier’s Extended Maildir++13.5.2. Installing Courier IMAP13.5.3. Courier IMAP and Pop-Before-SMTP13.5.4. Installing SqWebMail
14. Mailing Lists
14.1. Sending Mail to Lists14.1.1. Maintaining List Files14.1.2. Bounce Handling and VERP14.1.2.1. Manual bounce handling14.1.2.2. Automated bounce handling14.1.2.3. Bounce handling for mail without .qmail file forwarding14.2. Using Ezmlm with qmail14.2.1. Installing Ezmlm-idx14.2.2. Ezmlm List Names14.2.3. Creating an Ezmlm List14.2.4. Ezmlm Lists in Virtual Domains14.2.5. Sending Mail to and Testing an Ezmlm List14.2.6. Configuring and Maintaining an Ezmlm List14.2.7. Other Ezmlm Tricks and Features14.3. Using Other List Managers with Qmail14.3.1. Incoming Mail to List Managers14.3.2. Outgoing Mail from List Managers14.4. Sending Bulk Mail That’s Not All the Same
15. The Users Database
15.1. If There’s No Users Database15.2. Making the Users File15.3. How Qmail Uses the Users Database15.4. Typical Users Setup15.5. Adding Entries for Special Purposes15.5.1. Adding a Few Mail-Only Accounts15.5.2. Preparing for the POP Toaster
16. Logging, Analysis, and Tuning
16.1. What Qmail Logs16.2. Collecting and Analyzing Qmail Logs with Qmailanalog16.2.1. Log Analysis at Rotation Time16.2.2. Log Analysis Once a Day16.2.3. Getting Statistics with Qmailanalog16.3. Analyzing Other Logs16.4. Tuning Qmail16.4.1. Tuning Small Servers16.4.2. Tuning Large Servers16.5. Tuning to Deal with Spam16.6. Looking at the Mail Queue with qmail-qread
17. Many Qmails Make Light Work
17.1. Tools for Multiple Computers and Qmail17.1.1. Multiple Copies of Qmail17.1.2. mini-qmail17.1.3. Shared Mail Folders17.1.4. Multi-Host POP Toasters17.2. Setting Up mini-qmail17.2.1. Setting Up a QMQP Server17.2.2. Setting Up QMQP Clients17.2.3. Using QMQP17.2.3.1. Using a smarthost17.2.3.2. Setting up a mail firewall17.2.3.3. Mailing list load sharing
18. A Compendium of Tips and Tricks
18.1. Qmail Won’t Compile18.2. Why Qmail Is Delivering Mail Very Slowly18.3. Stuck Daemons and Deliveries18.3.1. Daemons Won’t Start, or They Start and Crash Every Few Seconds18.3.2. Nothing Gets Logged18.3.3. Daemons Are Running but Making No Progress18.3.4. Mail Rejected with Stray Newline Reports18.4. Mail to Valid Users Is Bouncing or Disappearing18.5. Mail Routing18.5.1. Sending All Mail to a Smarthost18.5.2. Treating a Few Remote Addresses as Local18.5.3. Slowing Mail Delivery to Certain Domains18.6. Local Mail Delivery Tricks18.6.1. Using a Subaddress Separator Character Other than Hyphen18.6.2. Customized Bounce Messages for Virtual Domains18.7. Delivering Mail on Intermittent Connections18.8. Limiting Users’ Mail Access18.9. Adding a Tag to Each Outgoing Message18.10. Logging All Mail18.11. Setting Mail Quotas and Deleting Stale Mail18.12. Backing Up and Restoring Your Mail Queue
A. A Sample Script
A.1. A Mail-to-News Gateway
B. Online Qmail Resources
B.1. Web SitesB.2. Mailing Lists
Index
About the Author
Colophon
Copyright

Content preview from qmail

Chapter 11. Remote Mail Delivery

Remote mail delivery is actually somewhat simpler than local mail delivery, because there’s really only one way to deliver remote mail: locate a suitable host for the message and deliver the mail to that host.

Telling Local from Remote Mail

Any domain that is listed in locals or virtualdomains is local. Anything else is remote. Note in particular that whether a domain appears in rcpthosts or morercpthosts has no bearing on whether it’s local or remote. (If a domain is in rcpthosts but isn’t local, that makes this host a backup or secondary MX for the domain, which I discuss later in this chapter.)

qmail-remote

As we saw in Chapter 2, the main qmail-send daemon passes remote deliveries to qmail-rspawn, which runs qmail-remote to attempt each delivery. The arguments to qmail-remote are the remote hostname, the envelope sender, and the envelope recipients, with the message to send on its standard input. Within qmail, qmail-remote is always run with a single recipient, and the host is the domain part of the recipient address. Other applications can use qmail-remote as a simple mail sending application, with as many recipients per message as desired.

Once qmail-remote has attempted delivery, it writes recipient report(s) and a message report to its standard output. The format of the reports is documented in the qmail-remote manpage.

Locating the Remote Mail Host

qmail-remote can identify the remote host for a message in two ways. If the smtproutes control ...

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