When I used sendmail, years ago, the smart host was defined in my local .mc file, which I edited from a prototype collection in the cf directory. Looking back at old prototypes for you now, I see the provision instruction looks like this:
Code:
dnl define(`SMART_HOST', `mail.myisp.net')dnl
The .mc file needs to be "compiled" into your final local .cf file with an applicable make command, or with the m4 processor directly. On OpenBSD, I vaguely recall using the m4 command directly, having switched first to the m4 directory. My memory may be faulty, because in order to find the provisioning data I grabbed the sendmail package for OpenBSD, and there are header files but no tools in the m4 directory there now. There's a Makefile in the .cf directory.
I hated sendmail. It worked, once provisioned, but provisioning was always a nightmare for me. Once OpenSMTPd became available, I left sendmail and never looked back.