In main as DMA had become the default MTA, there is a difference in its handling of command-line arguments. Consider a situation where /usr/sbin/sendmail is a link to /usr/sbin/mailwrapper, and /etc/mail/mailer.conf is set to use /usr/libexec/dma given the following simple script: #!/bin/sh body="Hello world" subject="Hello" emailsentfrom="$USER" emailgoesto="$USER1 $USER2" printf "From: ${emailsentfrom}\nTo: ${emaiilgoesto}\n \ Subject: "${subject}"\n\n${body}\n\n" \ | /usr/sbin/sendmail -oi -f ${emailsentfrom} ${emailgoesto} With sendmail, "${emailgoesto}" would properly expand to whomever $USER1 and $USER2 are, comma-separated, which is expected. With DMA, "${emailgoesto}" is not comma-separated, and are verbatim the expanded values "$USER1 $USER2", which is not expected.
(In reply to Glen Barber from comment #0) Correction to the printf part of the script: printf "From: ${emailsentfrom}\nTo: ${emaiilgoesto}\n \ Subject: ${subject}\n\n${body}\n\n" \ | /usr/sbin/sendmail -oi -f ${emailsentfrom} ${emailgoesto} There is only one pair of double-quotes.