Re: How best to eliminate "domain mismatch" warning in mail clients when TLS is used
- On 7/15/2013 3:14 PM, Wietse Venema wrote:
> Ben Johnson:This is the strongest argument that I've seen for adding SNI support to
>> On 7/15/2013 1:10 PM, Viktor Dukhovni wrote:
>>> On Mon, Jul 15, 2013 at 12:47:53PM -0400, Ben Johnson wrote:
>>>> In essence, our clients wish to use their own SSL certificates for their
>>>> SMTP connections.
>>> Are these submission clients? What does the above mean?
>> Yes, these are submission clients. To be clear, our clients want to be
>> able to configure their MUAs to use our MTA's submission service via
>> their own domain names. I know; it is not necessarily a rational or
>> reasonable request.
> It's entirely reasonable if they want to be able to change email
> provider without having to update all their clients.
Postfix. I hadn't even considered this. Maybe this is the basis for our
customers' respective positions; I wish they had made it clearer to
> Unfortunately there are not a lot of development cycles for addingI can't even imagine the complexities; I understand.
> a decent SNI implementation to Postfix.
In the meantime, I am all ears, regarding jf's question about SNI
proxying via, for example, nginx. If that subject is best addressed to
the nginx mailing list, I am happy to take the discussion to the
- Ben Johnson:
> In the meantime, I am all ears, regarding jf's question about SNIAccording to a thread in March 2013 they did not support SNI in the
> proxying via, for example, nginx. If that subject is best addressed to
> the nginx mailing list, I am happy to take the discussion to the
> appropriate list.
- On Mon, Jul 15, 2013 at 03:38:31PM -0400, Ben Johnson wrote:
> > It's entirely reasonable if they want to be able to change emailThere's a lot more to SNI support than having a server that can
> > provider without having to update all their clients.
> This is the strongest argument that I've seen for adding SNI support to
> Postfix. I hadn't even considered this. Maybe this is the basis for our
> customers' respective positions; I wish they had made it clearer to
> begin with.
context-switch between multiple certificates. You need a provisioning
system that allows clients to upload private keys and matching
certificates on a self-service basis via suitably authorized
You need to send the administrators reminders about iminent
certificate expiration, and alert your staff if they don't respond
promptly, so they ultimately get phone calls when they don't act
in a timely manner.
The whole thing is a major PITA for very little gain.
> > Unfortunately there are not a lot of development cycles for addingI have no time for this.
> > a decent SNI implementation to Postfix.
- On 7/15/2013 3:35 PM, Viktor Dukhovni wrote:
>>> Unfortunately there are not a lot of development cycles for addingAnd this is precisely why an entire VPS industry has sprouted over the
>>> a decent SNI implementation to Postfix.
> I have no time for this.
past few years. As someone stated down thread, give your customers what
they want and charge them accordingly. This is trivially easy to do
with your choice of hypervisor with memory consolidation (same page
merging) and a guest OS template. If your pool of IPv4 addresses is
limited charge them extra for that. If they're exhausted, well, you can
go IPv6 only but that really has downsides.
Here's an even better idea. Do what everyone else in your shoes does:
partner with a VPS provider and farm the bulk of this out. There are
tons of small companies that do exactly this. They buy X number of VPS
instances each with an IP address from a provider and rebrand them. The
VPS provider does all the heavy lifting WRT provisioning. You would
simply do the customization for your individual customers, i.e. DNS,
hostname, domain name, certificate, etc. A basic VPS for this kind of
thing can normally be had for well less than $10/month. The really
stripped down VPS services I see offered are $4.95/month. All prices
USD. If you already have a mailbox (IMAP/POP) server that currently
handles MX duty for all these customers, moving MX to these VPS
instances and relaying the mail to your mailbox server is easy as well.
- On 07/16/2013 05:30 AM, Ben Johnson wrote:
>> If your clients insist that a mail server is only professional if the TLSProbably the best option is to go old tech here. Get a separate IP for
>> session has their domain name written on it, then give them what they want at
>> the price it costs to implement it.
> Your position is perfectly reasonable, and is more or less the position
> that I've taken on the matter. I just wanted to be sure that there isn't
> some panacea that I had overlooked.
> In order to give our clients what they want, what are our choices?
each hostname that a client wants to connect to and set up separate
listeners in master.cf for each of those IPs with the appropriate TLS
options. Then let the clients buy their own cert and provide it to you
to use on the server. Up to you to come up with the additional pricing
for all of this. The extra dedicated IP is the first and most obvious
cost, the rest is administrative.
Keep in mind that you'll have to configure dovecot (or whatever you use
for IMAP/POP3) to listen on these other IPs and use those
customer-supplied certs as well.
Personally I would ramp up the extra fee even more to account for the,
"I don't want to do this really stupid unnecessary vain thing" reason.
I would make sure the client knows that they are just spending extra
money to satisfy their own vanity and if they still want to go ahead
then do it for them.