-f

-f

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Preserve case

V8.1 and above

Ordinarily, sendmail will normalize a key to lowercase before looking it up in a database. If the keys in the database are case-sensitive ("TEX" is considered different from "tex," for example), the -f database switch should be used to prevent this normalization. Note that if the -f switch is omitted (the default), the database must have been created with all lowercase keys (also the default).

Also note that when the -f switch is used with the regex database-map type, it causes the regular expression match to be made in a case-insensitive manner.