SixXS::Sunset 2017-06-06

microsoft outlook and ipv6-capable mailservers
[de] Shadow Hawkins on Wednesday, 12 May 2004 01:07:01
hi everyone, i recently - again - noticed problems with users reading their mail with microsoft outlook when using a mailserver which also got ipv6-dns-entries (aaaa): - when mailserver has ipv6-entries, ipv4-only-users can't connect, error: the server name could not be found. - when mailserver has no ipv6-entries, all users cann connect (only ipv4, of course) did anyone else notice this behavior of microsoft outlook? i ask, because i want to check if it's entirely outlooks fault not falling back to ipv4 if v6 is unavailable, or if it has something todo with the version of the underlying os, or precisely, the version of the underlying ipv6-stack. i'm using windows2000+sp4 with 'newest' available ipv6-testing implementation. one of the users on my mailserver which first noticed the problems has windows xp, unknown sp, no ipv6. sincerely, sebastian
microsoft outlook and ipv6-capable mailservers
[ch] Jeroen Massar SixXS Staff on Wednesday, 12 May 2004 09:13:30
Which "outlook" do you mean? Outlook Express or Office Outlook ? As they are quite different products. In both cases I can tell you that they *only* work using IPv4 addresses and have no notion of IPv6 at all unfortunatly. The only way you can get them to do IPv6 is to use "netsh int portproxy...." or nt6tunnel or a similar program. I have been using that for quite some time
- when mailserver has ipv6-entries, ipv4-only-users can't connect, error: the server name could not be found.
- when mailserver has no ipv6-entries, all users cann connect (only ipv4, of course)
This is a DNS server problem and not an issue at all for other programs. Try doing the following: - dig @yourcachingdns mail.example.net AAAA This should result in the IPv6 address - dig @yourcachingdns mail.example.net A This should result in your IPv4 address There are a couple of DNS servers though that return a "NODATA" in the first query because they don't understand AAAA's, thus "A" is not there either. If they would have responded the correct NOERROR the resolvers would also try the A itself. This was for instance a problem on the BBC nameservers

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