Username different from mailbox

[Torsten Schlabach]

Hi Patrick, hi all others,

This is *not* an MTA issue at all as soon as we discuss the IMAP user 
logging in rather than the MTA delivering mail!

This has been discussed indeed several times already and every time it 
came up, there were several people answering that they have no problem 
with that all. Yet unfortunately, they weren't talking about what was 
asked and what you need. (As long as I didn't get it wrong.)

It is crucial in this discussion to distingish between two things:

1. Teach the MTA (Exim, Postfix, doesn't really matter) that mail for 
x at y.com has to go to fillinwhatyoulike / what at have.you. Yes, this is a 
no-brainer. So we discuss SMTP here, which isn't really a subject for 
Cyrus IMAPd at all. And it's not what you're asking if I get it right.

2. In IMAP a user uses a name to identify himself against Cyrus IMAPd. 
The respective data is flowing right from the MUA (not the MTA) to port 
143. Note: No Exim / Postfix / qmail in the game.

Cyrus itself is indeed built on the assumtion that whatever name you use 
to authenticate *is* the name of the mailbox you want to see.

It is impossible to use any tricks in the LDAP backend to solve this. 
You will be able to make LDAP lookup the credentials for userb if he 
logs into Cyrus as usera (if you do whatever mapping in LDAP) but this 
will always result in a "no mailbox with that name error" as Cyrus IMAPd 
will authenticate correctly, but look for the wrong mailbox name.

The only way to solve your (and my) problem will be a canon_user SASL 
plugin, which does not yet exist.

Well, sort of ...

Howard Chu was so kind to write one which he provided to me as patch. 
Due to a lack of time and maybe ability I was yet unable to make it work 
for me. But I definitely trust him that when he says he had this working 
for him, that the problem is with me and not with his code.

So in case you are ready to compile your stuff from source, I will 
happliy share the patch with you and I would be extremely thankfull if 
you could help me with some hints on how to properly install that.

Regards,
Torsten


Jorey Bump schrieb:
> Patrick Kranz wrote:
> 
>> Now I have a customer, who needs the scenario that the usernames for 
>> Cyrus differ from the mailbox and mailaddress respectivly. For example 
>> user1 at testdomain.com should be able to login with the username 
>> someOtherUsername. This need arises from an integration with other 
>> software-packages. Is there any possibility to make this work?
> 
> 
> Yes, this is no different from any other alias or virtual setup that 
> offers multiple addresses to individual users. You would handle this in 
> the MTA. For example, I use virtual_alias_maps with Postfix, and map all 
> addresses to the corresponding cyrus IMAP user:
> 
>  abuse at example.com        admin
>  admin at example.com        admin
>  postmaster at example.com        admin
>  bob at example.com        bob
>  robert.smith at example.com    bob
> 
> You can also use the aliases file and other approaches.
> 
> 
> 
> ----
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