mail merge
combining mail and letters and pre-addressed envelopes or mailing labels for mass mailings from a form letter
en-GB/ˈmeɪl ˈmɜːd͡ʒ/
en-US/ˈmeɪl mɚd͡ʒ/
combining mail and letters and pre-addressed envelopes or mailing labels for mass mailings from a form letter