Most versions of Unix compilers provide environment variables to programs in the third argument to main( ). Others provide environment variables in an external pointer-variable called environ. If yours uses this latter approach, you can take advantage of it by defining this USE_ENVIRON compile-time macro:

APPENDDEF(`confENVDEF', `-DUSE_ENVIRON=1')  available with V8.12 and above

See Section 10.2 for a discussion of sendmail and the environment.

If you are running a precompiled sendmail binary, you can use the -d0.10 debugging command-line switch (-d0.10) to determine if USE_ENVIRON support is defined (if it appears in the list, it is defined).