sendmail[67546]: fatal: execvp /usr/sbin/postdrop: No such file or directory
postfix/sendmail[67545]: fatal: email@mail.com(5000): unable to execute /usr/sbin/postdrop -r: Success
dovecot: lda(rcpemail@mail.com): Error: Sendmail process terminated abnormally, exit status 75
dovecot: lda(rcpemail@mail.com): Error: sieve: msgid=<005701d35ec6$a2a11e80$e7e35b80$@mail.com>: failed to redirect message to <copytoemail@mail.com> (refer to server log for more information)

file /usr/sbin/postdrop
/usr/sbin/postdrop: setgid ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 3.0.0, BuildID[sha1]=55fb6e550abece72ccb01fb94213418d3ce75c72, stripped

ls -la /usr/sbin/postdrop
-rwxr-sr-x 1 root maildrop 15008 Feb 11  2015 /usr/sbin/postdrop