list = "john, john@gmail.com" "doe, doe@outlook.com" "jenny, jenny@another.domain"

for i,j in $list; do
    echo "Dear $i, email text" | mail -s "Hello $i" $j
done

echo "Dear john, email text" | mail -s "Hello john" john@gmail.com

name, email
john, john@gmail.com
jenny, jenny@another.domain
doe, doe@outlook.com