kumomta/docs/reference/headermap/set_to.md

set_to

headers:set_to(VALUE)

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

Assign VALUE to the To header.

VALUE may be either a string or 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.