Consequently, we recommend that in an NFS environment,
you set the default user to one less than nobody.* For example, if nobody has the uid
65534, you could set up:
mailnull:*:65533:65533:Sendmail Default User:/no/such/directory:/bin/false
4.8.2.2 The RunAsUser option (V8.8 and above)
The RunAsUser option (?§24.9.102 on page 1083) is just like the DefaultUser option
(?§24.9.32 on page 1000) described earlier. But instead of setting the identity to be
used when sendmail is not running as root, this option sets the identity to replace
root. Because a non-root program cannot assume the identity of other users, this
option cannot be used in conjunction withth e DefaultUser option. Instead, this
option sets the only identity that sendmail will use.
Although it is tricky to get sendmail to run as a non-root process in all circumstances,
V8.12 offers a way to get part of sendmail to do this. The idea is that initial
mail submission (by local users) can be sent safely witha non-root sendmail, whereas
handling inbound mail and local delivery can require a root process. V8.12 handles
this division by creating two separate sendmail processes, handling the two separate
roles. See ?§2.5 on page 60 for a complete explanation of this process.
4.8.2.3 The TrustedUser option (V8.10 and above)
The TrustedUser option (?§24.9.122 on page 1112) defines the user that can administer
sendmail.
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