that begins the delivery agent definition command is immediately
followed, with no intervening whitespace, by the name of the delivery
agent. Note that the name is symbolic and is used only internally by
sendmail. The name can contain no whitespace,
and if it is quoted, the quotation marks are interpreted as part of
its name. In the following, only the first is a good symbolic name:
Mlocal ← name is local, good M local ← error: name required for mailer Mmy mailer ← error: mailer my: `=' expected M"mymailer"← quotation marks are retained
Although the symbolic name can contain any character other than a space or a comma, only letters, digits, dashes, and underscore characters are recommended:
Mprog-mailer ← name is prog-mailer, good Mprog_mailer ← name is prog_mailer, good Mmymailer[ ]; ← name contains [ ];—avoid such characters
The symbolic name is not case-sensitive; that is,
LOCAL are all identical.
Note that if two delivery agents have the same name, all the delivery agent equates for the second definition replace those for the first. Therefore, the last definition for a particular symbolic name is the one that is used.
agent is required, so if that
required definition is missing, sendmail prints the following warning ...