SWAKS

for i in recipient@example.invalid ; do swaks -s localhost -p 25 --from sender@example.invalid --h-From: '"First Sur" <sender@example.invalid>' --to recipient-bcc@example.invalid,$i --h-To: "$i" --h-Subject: 'subject line' -h-Content-Type: 'text/plain; charset="UTF-8"' -h-Content-Transfer-Encoding: '8bit'  -b ./file.txt ; done