dovecot - Oct 2020 - Looking for a guide to collect all e-mail from the ISP mail server

I remember back in the dialup era there was a small company in Timisoara 
who tried to sell this kind of solution. (They started to sell servers 
after a while so I guess they didn't have much success selling? their 
workaround) So I guess it is not trivial to sort again all the mails and 
deliver each one in a mailbox after you mixed all together in a single 
catchall mailbox. Could be done for sure but it is some work to do...? 
Also there is some management: what to do with the catchall mailbox? 
Delete each mail after successfully downloaded? Use IMAP and sync it for 
a while to have a backup?

On 10/26/20 6:34 PM, Michael Schumacher wrote:
> [...]
>> I could not find anything there related to multidrop or "catch
all" mailboxes.
> [...]
>> Nothing like that there either.
> [...]
>> This is a huge document with little introduction. It seems to be
>> mostly about fighting spam. I did not find anything like the setup I
described.
> looks like the collective wisdom of this group can't provide precisely
> what you are looking for. You may need to figure it out by yourself.
>
> Btw., why is an open port 25 evil if the MTA is configured correctly?
> Can you elaborate, please?
>
> best regards
> ---
> Michael Schumacher
>

On 26.10.20 17:45, Mihai Badici wrote:
> So I guess it is not trivial to sort again all the mails and
> deliver each one in a mailbox after you mixed all together in a single
> catchall mailbox. Could be done for sure but it is some work to do...?
Determining the intended recipient of a specific *copy* of an e-mail
(info contained in the envelope) from that copy *after* "final"
delivery
(at the ISP, no more envelope, info *possibly* contained in pseudo
headers of varying name and reliability) is *most definitely*
nontrivial, and (used to be?) known as a prime cause of mail loops.

If you don't know *exactly* what you're doing, maintain your myriad of
users/mailboxes *both* at the ISP and on your internal servers and put
the "mails in ISP mailbox X *all* go into internal mailbox Y, and
nowhere else!" relations "hardcoded" into your retrieval
tool's config.

Regards,
-- 
Jochen Bern
Systemingenieur

Binect GmbH

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On 10/26/20 7:53 PM, Jochen Bern wrote:
> On 26.10.20 17:45, Mihai Badici wrote:
>> So I guess it is not trivial to sort again all the mails and
>> deliver each one in a mailbox after you mixed all together in a single
>> catchall mailbox. Could be done for sure but it is some work to do...
> Determining the intended recipient of a specific *copy* of an e-mail
> (info contained in the envelope) from that copy *after* "final"
delivery
> (at the ISP, no more envelope, info *possibly* contained in pseudo
> headers of varying name and reliability) is *most definitely*
> nontrivial, and (used to be?) known as a prime cause of mail loops.
>
> If you don't know *exactly* what you're doing, maintain your myriad
of
> users/mailboxes *both* at the ISP and on your internal servers and put
> the "mails in ISP mailbox X *all* go into internal mailbox Y, and
> nowhere else!" relations "hardcoded" into your retrieval
tool's config.
>
> Regards,
That's exactly why I recommended? to use smtp relay. Maintaining two 
user's database without any? password sync mechanism available it's 
asking for trouble. Well, with under 10 user you can manage...

As a bonus, you have a near "real mail system" and you eventually
learn
to manage it :)