sendmail, 4th Edition

Section 6.2

Timeouts can be used to improve sending performance. Some timeouts, such as Timeout.resolver. retry , are new (V8.10 and later).

Section 6.3.2

The discard delivery agent can be used to handle bounced email (V8.9 and later).

Section 6.3.3

The Local_check_rcpt rule can be used to create a mail- reception black hole (V8.8 and later).

Section 6.4

Buffered file I/O improves sending performance (V8.12 and later).

Section 6.5

Multiple queues and queue groups aid queue performance (V8.12 and later).