kumomta/docs/reference/headermap/set_bcc.md

set_bcc

headers:set_bcc(VALUE)

{{since('2025.10.06-5ec871ab')}}

Assign the VALUE to the Bcc header.

VALUE may be either a string or be an AddressList.

If you assign using a string, the string will be parsed and validated as being compatible with AddressList before allowing the assigment to proceed.