Auto MX Email Client configuration, the right way?

[Davide Marchi]

Hi Friends!
An opinion.

I would like to facilitate the configuration of one's mail client 
(desktop or mobile) to my users server.
Some time ago I asked the same question and you suggested me to use 
"Automx".

So I started of good will and I looked for the Automx documentation. And 
here the problems started as I found several inconsistencies, even 
parameters (in official documentation) that produce Apache errors..
to complicate things, different path between deb packages and official 
version :-)

Now I've seen the new RFC 6186 specification 
(https://tools.ietf.org/html/rfc6186) that describe a "DNS way" to 
achieve the same goal.

[..]
4.  Guidance for MUAs

    By using SRV records as above, MUAs need initially only to prompt the
    user for their email address [RFC5322].  The "local-part" and
    "domain" portions are then extracted from the email address by the
    MUA.  The MUA uses the "domain" portion as the service domain to
    perform SRV lookups for the services it wants to configure.  If the
    SRV lookup is successful, the target FQDN and port for the service
    can be determined and used to complete MUA configuration.  If an SRV
    record is not found, the MUA will need to prompt the user to enter
    the FQDN and port information directly, or use some other heuristic.
    In the case of multiple SRV records returned for a particular
    service, the MUA MUST use the priority and weight fields in the
    record to determine which one to use (as per [RFC2782]).

[..]

again:
    [..]
    When a user identifier is required, MUAs MUST first
    use the full email address provided by the user, and if that results
    in an authentication failure, SHOULD fall back to using the "local-
    part" extracted from the email address.  This is in line with the
    guidance outlined in Section 5.  If both these user identifiers
    result in authentication failure, the MUA SHOULD prompt the user for
    a valid identifier.
    [..]

here I have the biggest doubt, in fact Thunderbird often uses only the 
username and not the whole email address, both for incoming and outgoing 
server...
Is any of you using this second way? And possibly, do you kniw if it 
works with different clients (desktop and mobile)?


Many many thanks!

Davide