May 26, 2018

Speeds delivery to mailing lists by sorting & batching addresses

This is a C program to do “bulk” mailing. For input, it takes a file of recipient addresses one address per line and a message with headers already attached to be sent to the recipients. It sorts the recipient list by reversed domain so similar ones sort together, splits up the recipients into several groups containing no more than N domains each, creates an SMTP envelope for each group of recipients, and feeds that envelope to “/usr/sbin/sendmail -bs”.