sendmail, 4th Edition

OldStyleHeaders

Allow spaces in recipient lists All versions

In pre-RFC821 days, lists of recipients were commonly space-delimited; that is, the list:

hans christian andersen

was considered a list of three mail recipients, rather than a single, three-part name. Currently, individual recipient names must be delimited with commas, and internal spaces must be quoted. That is:

hans,christian,andersen       ← three recipients
"hans christian andersen"     ← a single three-part name
hans christian andersen       ← illegal

Because some users and some old programs still delimit recipient lists with spaces, the OldStyleHeaders option can be used to tell sendmail to internally convert those spaces to commas.

The forms of the OldStyleHeaders option are as follows:

O OldStyleHeaders=bool                 ← configuration file (V8.7 and later)
-OOldStyleHeaders=bool                 ← command line (V8.7 and later)
define(`confOLD_STYLE_HEADERS',bool)   ← mc configuration (V8.7 and later)
Oobool                                 ← configuration file (deprecated)
-oobool                                ← command line (deprecated)

The argument bool is of type Boolean. If that argument is missing, the default value is true, and unquoted spaces in an address are converted to commas. The default when configuring with the mc technique is true. If the entire OldStyleHeaders option is missing, it defaults to false, and unquoted spaces are converted to the character defined by the BlankSub option (BlankSub on page 980).

The sendmail program is somewhat adaptive about commas. When first examining a list of addresses, it looks to ...