Postfix mailq - send every x minutes

Question

I got about 2000 clients on my website that have subscribed to our mailing list. I've used in the past Swift Mailer but it didn't work the way it was supposed to.

I'm wondering if there is a way that Postfix could keep emails on the mailq (if lots of emails are sent at the same time) and send chunks of 20-30 emails every 10-20 mins. So this way, our server is not blacklisted.

Any suggestions will be appreciate it.

Answer 1

If I understand the question correctly, you can do this using the default_destination_rate_delay and default_destination_recipient_limit parameters.

• default_destination_rate_delay specifies a delay between deliveries. You would set this to 10-20 mins.
• default_destination_recipient_limit specifies the number of recipients to send email to in one delivery. Assuming you are sending one single message to many recipients, you would set this to 20-30, according to your question.

Answer 2

Are you limited to using postfix? This is doable with Exim.

Inbound exim set to queue only, configure outbound exim, cron exim -bpu | grep '<' | head -20 | awk '{print $3}' | xargs exim -Mc every 10 mins, or something to that effect

Answer 3

It's kind of an ugly hack, but you could use the Postfix HOLD queue and release batches of messages usng postsuper -H via a cron job.

You'll need some sort of smtpd access map that identifies list mail to be put on HOLD.