#783 accepted
Bjoern A. Zeeb

Not IPv6 ready

Reported by Bjoern A. Zeeb | May 21st, 2014 @ 10:52 PM


the very first impression on trying to get to a mail server when importing the Mail.app profile things failed already.
It seemed the reason was that the server was IPv6-only (server only has an AAAA record/an IPv6 address). Had to close and forget MailMate for now :-(

Comments and changes to this ticket

  • benny

    benny May 22nd, 2014 @ 12:15 PM

    • State changed from “new” to “accepted”

    Thanks for the feedback. As you might have guessed I've never tested MailMate with an IPv6-only mail server. MailMate uses OpenSSL and I believe this is the main reason it doesn't work now (after googling a bit). The plan is to switch to CFNetwork (Apple framework) and I assume this would also fix this issue. I'll update this ticket if there is any progress on that in case you want to retry MailMate in the future.

  • Bjoern A. Zeeb

    Bjoern A. Zeeb May 22nd, 2014 @ 12:35 PM

    Yes openssl has certain issues (at least s_client) does. There are patches floating around in gentoo/openssl bug tracker/FreeBSD's SoC SVN from a few years ago. In general a lot of the software using openssl for TLS does seem to support IPv6(-only). So probably depends on code. Apple themselves do have some issues as well in the framework, but most problems I am aware of are on iOS; or in case of dual-stack preferring IPv4, which is fine as it works.

    Very impressed by your response time! This is amazing and gives me great confidence that I'll try using MailMate once this is sorted and happily pay for it :-) Also happy to beta-test IPv6 things for you if needed.

  • Paul

    Paul May 20th, 2015 @ 07:58 PM

    Hi Benny,

    Could you give an update on IPv6 support?

    My mail services (SMTP and IMAP) both support v6 and work with Apple Mail when I have a v6-only connection.

    With MailMate I cannot seem synchronise by Inbox via IPv6, and there is not evidence of any activity in the Activity Viewer. When I try to send an email, there is also no activity reported, and then after a timeout I get this error:

    Failed connecting to host (exch-smtp.apnic.net:465).
    “error:02002040:system library:connect:Host is down”
    “error:20073067:BIO routines:CONN_STATE:connect error”
    Tip: Open the Activity Viewer (⌥⌘0) before retrying. The SMTP log file might provide additional information.



  • benny

    benny May 21st, 2015 @ 07:56 AM

    @Paul: Unfortunately there is no progress on this issue. The plan is still the same (switching to an Apple framework).

    (It's surprisingly rare that this issue comes up, but it's still a priority for me to fix it -- eventually.)

  • Bjoern A. Zeeb

    Bjoern A. Zeeb May 21st, 2015 @ 10:34 AM


    Would it help if a new version of OpenSSL in the mean time would be working properly with IPv6?
    Would it be possible for you to possibly make minor modifications to MailMate (rather than switching to the entire Crapple Core Framework) to make that going in the not too distant future if OpenSSL was ready for it?
    I could possibly help to see that the OpenSSL side happens if it hasn't fully happened yet (I lost track honestly;)

    Let me know if I should try (it needs to happen there anyway, just another good reason ;-)

  • benny

    benny May 21st, 2015 @ 10:44 AM

    @Zeeb: The path of least resistance for me is probably CFNetwork (there is also an issue with proxy support.) The main reason I chose OpenSSL originally is that I generally prefer cross-platform code (just in case), but in this case I think this was a mistake — or I should at least have made it easier to replace the network interface.

  • Bjoern A. Zeeb

    Bjoern A. Zeeb March 22nd, 2016 @ 12:09 PM

    With Apple's policy that Apps must support IPv6(-only) (and they'll soon enforce it for what goes through their hands) it would be really really great if MailMate could be part of that IPv6-supporting family, either through openssl or through their Framework. I can't say how much work it is but if you need any help in terms of testers, or other resources, please please let me know :)

  • benny

    benny March 25th, 2016 @ 06:24 AM

    @Zeeb: When it happens then it'll definitely be via the CFNetwork framework, but I haven't made any progress yet. Thanks for offering to help out.

  • benny

    benny April 21st, 2016 @ 10:17 AM

    @Zeeb: If you are still willing to test IPv6 support then send me an email (Help ▸ Send Feedback). I've been working on switching to CFNetwork.

  • Christopher Liljenstolpe

    Christopher Liljenstolpe May 11th, 2016 @ 06:20 PM

    @benny I would also be willing to test IPv6. I'm unable to do e-mail at the @Scale event - IPv6 only.

    I can recreate at home.

  • benny

    benny May 11th, 2016 @ 06:21 PM

    @Christopher: I'll write you an email. I have a revision of MailMate which should work with IPv6.

  • Olaf

    Olaf May 20th, 2016 @ 12:37 PM


    I am back in an IPv6 enabled environment with build 6021: I think you nailed it connections over IMAP and SMTP to servers that only have AAAA seem to work.



  • benny

    benny May 21st, 2016 @ 07:42 AM

    • State changed from “accepted” to “fixcommitted”

    @Olaf: Thanks for the update.

  • benny

    benny September 15th, 2016 @ 03:57 PM

    • State changed from “fixcommitted” to “fixreleased”

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