the problem with ping is if the host is not alive often your local machine will return an answer that the pinged host is not available, thus the errorcode of ping will be 0 and your code will run in error because not recognizing the down state.
better do it this way
ping -n 4 %1 | findstr TTL
if %errorlevel%==0 (goto :eof) else (goto :error)
this way you look for a typical string ttl which is always in the well done ping result and check error on this findstr instead of irritating ping
overall this looks like this:
@echo off
SetLocal
set log=path/to/logfile.txt
set check=path/to/checkfile.txt
:start
echo. some echo date >>%log%
:check
for /f %%r in (%check%) do (call :ping %%r)
goto :eof
:ping
ping -n 4 %1 | findstr TTL
if %errorlevel%==0 (goto :eof) else (goto :error)
:error
echo. some errormessage to >>%log%
echo. some blat to mail?
:eof
echo. some good message to >>%log%