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Sendmail, 3rd Edition by Bryan Costales

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Using Multiple Queue Directories

Beginning with V8.10, sendmail allows the use of multiple queue directories. These multiple queue directories take two forms:

  • More than one queue directory can be specified, possibly on separate disks, into which all the qf, df, and xf files are placed.

  • Any queue directory can have a subdirectory named qf, and/or df, and/or xf, in which sendmail stores the corresponding qf, df, and xf files.

Multiple Queue Directories

V8.10 sendmail offers the ability to distribute queued messages across multiple directories. In general, this is a good idea. If, for example, a high volume of email is stressing your current disk, you can improve efficiency by using multiple queue directories spread over multiple disks and controllers.

To illustrate, we will set up a machine that has three brand-new disks to use as multiple queue directories. The disks have already been formatted and a filesystem has been placed on each. We next create directories on which to mount them:

# mkdir /var/queues /var/queues/q.1 /var/queues/q.2 /var/queues/q.3
#chmod 700 /var/queues /var/queues/q.?

Because of the way multiple queue directories are implemented inside sendmail, the queue directory names must differ only in their suffixes, hence the trailing 1, 2, and 3. First the directories are created with mkdir(1) or a symbolic link, then the permission on each is reduced to readable and writable only by root for security reasons. Note that these are the permissions after all queue disks ...

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