users are not getting confirmation emails when registering for forum

[Be]

A handful of users have come by IRC lately saying they did not get a confirmation email when registering for the forum.

[ronso0 (ronso0)]

..and I'm wondering why I don't get email notifications for new replies.

[RJ Skerry-Ryan (rryan)]

Looks like the problem is that 69.195.146.38 (our VPS) does not have a PTR record pointing to mixxx.org. I've asked Garth if his VPS provider supports PTR records. I don't think all email is getting rejected, just some mail servers that check rDNS.

Here are the mail servers we seem to be dropping from the most (going back to January 8)
      2 idcmail-mx1so.cg.shawcable.net
      2 idcmail-mx2no.cg.shawcable.net
     24 mailin-01.mx.aol.com
     24 mailin-02.mx.aol.com
     24 mailin-03.mx.aol.com
     24 mailin-04.mx.aol.com
      4 mx00.emig.gmx.net
      4 mx00.gmx.net
      1 mx00.mail.com
      4 mx01.emig.gmx.net
      4 mx01.gmx.net
      1 mx01.mail.com
      1 mx.bt.lon5.cpcloud.co.uk
      5 mx-ha02.web.de
      5 mx-ha03.web.de
      2 mx.talktalk.net
      4 smtp.glb.shawcable.net

[RJ Skerry-Ryan (rryan)]

As of March 12, 2017 we got a PTR record for 69.195.146.38 mapping to mixxx.org. The rate of mail rejects dropped precipitously on that day based on our postfix logs.

The only rejected emails I've seen after March 12th (other than normal stuff like accounts no longer existing, full mailboxes, etc.) have been from AOL, e.g.:

Mar 20 07:31:03 mixxx postfix/smtp[25097]: 5B8098029B: host mailin-02.mx.aol.com[152.163.0.68] refused to talk to me: 554- (RTR:BB) https://postmaster.aol.com/error-codes#554rtrbb 554 Connecting IP: 69.195.146.38

telnet'ing to an AOL mx prints the following:
$ telnet mailin-01.mx.aol.com 25
Trying 64.12.91.195...
Connected to mailin-01.mx.aol.com.
Escape character is '^]'.
220-mtaig-mac03.mx.aol.com ESMTP Internet Inbound
220-AOL and its affiliated companies do not
220-authorize the use of its proprietary computers and computer
220-networks to accept, transmit, or distribute unsolicited bulk
220-e-mail sent from the internet.
220-Effective immediately:
220-AOL may no longer accept connections from IP addresses
220 which no do not have reverse-DNS (PTR records) assigned.
421 4.4.2 mtaig-mac03.mx.aol.com Error: timeout exceeded

But we do have a PTR record.
I submitted a postmaster ticket with AOL using this form:
https://postmaster.aol.com/sa-ticket
We'll see what they say.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/8768