On 02/04/2015 03:46 PM, Noel Jones wrote:
On 2/4/2015 1:47 PM, Robert Moskowitz wrote:
I have been 'working' with my new ISP for a couple weeks to get the
rDNS setup for my server move (I am changing ISPs for a number of
reasons). I was assured on signing that setting up rDNS was 'easy';
it is not. DIGing up the SOA on my IP rDNS tends to indicate that
they have not updated that zone for many months.
Anyway,,,
A friend using the same ISP 'solved' this by changing his SMTP
server to say the mail for his domain is ok to come from the ISP PTR
value. So let's say that:
My server is: z9m9z.htt-consult.com
And further assume that the reverse for the address where I want to
move it to has a PTR of
9.254.253.50.in-addr.arpa. 3600 IN PTR
50-253-254-9-static.hfc.comcastbusiness.net.
And that 50-253-254-9-static.hfc.comcastbusiness.net has no RR (e.g.
A or CNAME).
Is there someway to get postfix to provide the needed inforation to
the recipient MTA that this is OK and valid?
I am asking, but I suspect that even if I send out things OK, there
will be MTAs out there that will not let their clients send mail to
me as my rDNS does not match.
I am pushing the ISP that will remain unnamed. (oops. :) ) I was
told that 'they are working on it'. Meanwhile I am paying double as
I cannot migrate my server.
I will be pleased if there is a real workaround, but not overly
disappointed if the only way out is through.
Don't worry about *receiving* mail.
Other systems sending you mail don't care a bit about what the name
of your MX server is, or what kind of IP it's hosted on, as long as
the MX name resolves to the correct IP. Feel free to reuse your
current z9m9z.htt-consult.com as an MX name, or use something
totally different.
There are potential problems with *sending* mail.
All the comcast business IPs that I know of already have proper
FCrDNS. This is necessary to communicate with sites that use
"reject_unknown_client_hostname" or similar.
If they run your domain (at an additional cost), they take care of the
rDNS. If not, you have to put a request in that gets bounced around a
couple of times until someone figures out what you are asking about.
If your new IP's PTR has no matching A record, get that solved first
before you tackle trying to get a custom PTR. This should be an
easier problem to fix.
I will change my A record only after the PTR is created. If I change my
A record first by adding it as a second A record, any server that tries
it will get a connection failure as I have not moved my system yet. If
I change my A record and move the system before the rDNS is done, I am
back to that mess I got myself in before with a bad rDNS floating around.
The only way I see for a smooth migration of an existing server is:
1) setup rDNS - this hurts no one, as since nothing is on the address,
no one is doing an rDNS lookup.
2) move the server and change forward DNS (set TTL low at first).
Done. (restore TTL to longer value)
Once you have FCrDNS (even with an unwanted PTR name), you should be
able to safely move. Do some testing -- just hook some PC up to the
new connection and use telnet (or the very handy mini_smtp tool) to
send some test mails directly to various servers.
I have a web server already over there that I can test from. What
little I do web wise is not bothered by no rDNS. Now moving the DNS
server itself will be a fun adventure. I already have all the zone
files redone for the move.
Configure postfix with a HELO name (smtp_helo_name) something like
"z9m9z.htt-consult.com" rather than the more technically correct PTR
name. Make sure the HELO hostname has an A record pointing to your
IP. (bonus points for a name containing smtp, e?mail, mx, mta,
etc.) This helps you look more like a mail server and less like a bot.
Make sure you have an SPF record including your IP. If you use the
same IP for sending and receiving, just include the spf "mx" key.
(looks as if you have that already... good)
