Determining if the function smtp_create_session exists in the esmtpDoNotFindMe failed with the following output:
Change Dir: /var/tmp/portage/dev-libs/log4cxx-1.0.0/work/apache-log4cxx-1.0.0_build/CMakeFiles/CMakeScratch/TryCompile-HSb0Oc

Run Build Command(s):/usr/bin/ninja cmTC_eeaed && [1/2] Building CXX object CMakeFiles/cmTC_eeaed.dir/CheckFunctionExists.cxx.o
[2/2] Linking CXX executable cmTC_eeaed
FAILED: cmTC_eeaed 
: && /usr/bin/x86_64-pc-linux-gnu-g++ -O2 -march=x86-64 -pipe -pipe -frecord-gcc-switches -fno-diagnostics-color -fmessage-length=0 -DCHECK_FUNCTION_EXISTS=smtp_create_session -Wl,-O1 -Wl,--as-needed -Wl,--defsym=__gentoo_check_ldflags__=0 CMakeFiles/cmTC_eeaed.dir/CheckFunctionExists.cxx.o -o cmTC_eeaed  -lesmtpDoNotFindMe && :
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: cannot find -lesmtpDoNotFindMe: No such file or directory
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.