Manual:$wgAdditionalMailParams

Email settings: $wgAdditionalMailParams
Additional email parameters, will be passed as the last argument to mail() PHP function call.
Introduced in version:1.17.0 (r75557)
Removed in version:Still in use
Allowed values:(string) or null
Default value:null

Details

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Additional email parameters, will be passed as the last argument (additional_parameters) to the PHP mail() function call. See the documentation of the mail() function.

Ignored when $wgSMTP is set.