Interrelating Options
At the end of this chapter we list all the options in alphabetical order for easy lookup and explain each in detail. Here, we present them grouped by application with only a brief description.
File Locations
The only file that sendmail knows the location of is its configuration file. [3] Options in the configuration file tell sendmail where all other files and directories are located. The options that specify file locations are summarized in Table 34.6. All file location options are of type string.
[3] Beginning with V8.6 sendmail, it also knows the location of its pid file.
| Option Name | File | ||
|---|---|---|---|
| AliasFile | (A)
| Aliases file and its database files | |
| ErrorHeader | (E)
| Set error message file | |
| ForwardPath | (J)
| Set ~/.forward search path | |
| HelpFile | (H)
| Specify location of the help file | |
| HostsFile | Specify alternate /etc/hosts file | ||
| QueueDirectory | (Q)
| Location of queue directory | |
| SafeFileEnvironment | Directory for safe file writes | ||
| ServiceSwitchFile | Specify file for switched services | ||
| StatusFile | (S)
| Statistics file | |
| UserDatabaseSpec | (U)
| Specify user database |
File locations should be expressed as full pathnames. Use of relative names will cause the location to become relative to the queue directory or, for some options, will cause the name to be interpreted as something other than a file or directory name.
The Queue
Several options combine to determine your site's policy for managing the sendmail queue (see The Queue). Among them is one that specifies the location of the queue directory and another that sets the permissions given to files in that directory. The list of all options that affect the queue is shown in Table 34.7.
| Option Name | Description | ||
|---|---|---|---|
| CheckpointInterval | (C)
| Checkpoint the queue | |
| ForkEachJob | (Y)
| Process queue files individually | |
| MaxQueueRunSize | Max queue messages processed | ||
| MinFreeBlocks | (b)
| Define minimum free disk blocks | |
| MinQueueAge | Skip queue file if too young | ||
| QueueDirectory | (Q)
| Location of queue directory | |
| QueueFactor | (q)
| Factor for high-load queuing | |
| QueueLA | (x)
| On high load queue only | |
| QueueSortOrder | How to presort the queue | ||
| QueueTimeout | (T)
| Limit life in queue to days | |
| RecipientFactor | (y)
| Penalize large recipient lists | |
| RetryFactor | (Z)
| Increment per job priority | |
| SuperSafe | (s)
| Queue everything just in case | |
| TempFileMode | (F)
| Permissions for temporary files | |
| Timeout.queuereturn | Timeout life in queue | ||
| Timeout.queuewarn | Timeout for still-in-queue warnings |
Managing Aliases
In addition to knowing the location of the aliases file, some options determine how that file and its associated database files will be used. For example, there is an option that tells sendmail to automatically rebuild the database files whenever the aliases file is changed. The list of all aliases-related options is shown in Table 34.8.
| Option Name | Description | ||
|---|---|---|---|
| AliasFile | (A)
| Define the location of the aliases file | |
| AliasWait | (a)
| Wait for aliases file rebuild | |
| AutoRebuildAliases | (D)
| Autorebuild the aliases database | |
| CheckAliases | (n)
| Check right-hand side of aliases | |
| ServiceSwitchFile | Specify file for switched services |
Controlling Machine Load
Several options control the sendmail program's behavior under high-machine-load conditions. They are intended to reduce the impact of sendmail on machines that provide other services and to help protect sendmail from overburdening a machine. The list of options that determine and help to prevent high-load conditions is shown in Table 34.9.
| Option Name | Description | ||
|---|---|---|---|
| ClassFactor | (z)
| Multiplier for priority increments | |
| ConnectionRateThrottle | Incoming SMTP connection rate | ||
| HoldExpensive | (c)
| Queue for expensive mailers | |
| MaxDaemonChildren | Maximum forked children | ||
| MinQueueAge | Skip queue file if too young | ||
| QueueFactor | (q)
| Factor for high-load queuing | |
| QueueLA | (x)
| On high load queue only | |
| RefuseLA | (X)
| Refuse connections on high load |
Connection Caching
V8 sendmail has connection caching to improve the performance of SMTP-transported mail. In processing the queue or delivering to a long list of recipients, keeping a few SMTP connections open (in case another message is for one of those same sites) improves the speed of transfers. Caching is most useful on busy mail hub machines but can benefit any machine that sends a great deal of network mail. Table 34.10 lists the options for how connections will be cached.
| Option Name | Description | ||
|---|---|---|---|
| ConnectionCacheSize | (k)
| Multiple-SMTP connections | |
| ConnectionCacheTimeout | (K)
| Multiple-SMTP timeouts |
The sendmail program checks its connection cache just before opening up a new connection to a host. If the cache contains an entry for that host, sendmail sends an SMTP RSET command to the host to make sure the connection is still active. If the SMTP RSET succeeds, the connection is re-used. If the SMTP RSET times out (see , the Timeout.rset option), or fails, or if the host was not in the cache, an new connection is made.
Problem Solving
The sendmail program offers four options that will help in locating and solving some mail delivery problems. You are encouraged to enable the first two shown in Table 34.11. The third is of value only if you have many delivery agents (see Delivery Agents).
| Option Name | Description | ||
|---|---|---|---|
| LogLevel | (L)
| Set (increase) logging level | |
| PostmasterCopy | (P)
| Extra copies of postmaster mail (not V5 BSD) | |
| StatusFile | (S)
| Specify statistics fil | |
| Verbose | (v)
| Run in verbose mod |
Other means to solve problems are described in Debugging with -d, which describes the -d debugging command-line switch, and in The Command Line, (specifically "Processing the Command Line"), which describes the -X traffic-logging command-line switch.
Other Options
The sendmail program supports a vast array of options. Take the time to study all the options (described at the end of this chapter) at least enough to get a basic feeling for what they do. Then, as you gain experience with sendmail, you'll know where to look for the particular option that will meet your needs.