Hello, I know this question has been discussed on this list* but no suitable solution was provided for our SMTP server settings. A patch** is published but reports on this list say that it does not work.
I am responsible for a medium sized mailing-list, through which one email is sent per day to roughly 600 000 subscribers. Since our mailing list is growing, we are having more and more problems with very conservative SMTP servers enforcing a low number of simultaneous connections from a single IP address. Our subscribers wish to receive their email as soon as possible so delaying the email for a few hours is not an option. I was thinking of allocating 4 IP aliases for our SMTP server so that connections would appear to come from different servers. The goal is not to flood*** the target server as our own postfix server has its own limit to the number of simultaneous active connections, set to 30 connections. The application uses the "sendmail" binary to send email, and not SMTP. One email is sent per subscriber and signed with dkimproxy plugged onto the "pickup" daemon. Each email is always sent from the same nore...@mydomain.org address. Is it possible to tell postfix to randomly select an IP address, and associated hostname (as many smtp servers perform RDNS lookups and compare it to the HELO/EHLO greeting) when sending an email ? That would be very helpful. Regards, David. (*) http://www.mail-archive.com/postfix-users@postfix.org/msg18400.html & http://www.mailinglistarchive.com/postfix-users@postfix.org/msg57399.html (**) http://denixsolutions.com/Scripts/Postfix-Multiple-Interfaces-Patch (***) At this stage I feel it is necessary to stress that the mailing-list is not for profit and that we take every step to make sure that subscribers who change their mind are unsubscribed as soon as possible. We use confirmed opt-in (aka "double opt-in") for subscription, simplified unsubscription, every RFC compliant headers required for bulk emailing, VERP, SPF, DKIM, complaint feedback loop with ARF with most providers etc in order to maintain a high deliverability ratio. I am not willing to give the name of the organisation so you will have to take my word for it.
