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

Why don't you configure all stuff internally and ask your provider to 
relay the e-mails from and to you via "smart relay"?? You will 
communicate only via smtp and only with your provider, and you can use a 
nice open-source bundle ( dovecot is mandatory because you wrote on that 
list :) ) in your LAN.
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> 	? Original Message  	
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> From: rdiezmail-2006 at yahoo.de
> Sent: October 25, 2020 10:57 AM
> To: dovecot at dovecot.org
> Subject: Looking for a guide to collect all e-mail from the ISP mail server
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> Hi all:
>
> I am evaluating mail server solutions for a small business. The trouble is,
I am only a part-time admin and a newbie to mail servers.
>
> Most guides I have seen are rather unrealistic: they encourage you to
expose your e-mail server to the Internet, and hope that you have the resources
> to keep it patched up.
>
> I would rather have an internal mail server that collects e-mails from a
standard ISP mail server.? It is like the old "POP3 Connector" that
came with
> Microsoft Exchange.? Sometimes, there is a mailbox per user on the ISP, and
a corresponding one on the local server.? Other times, there is a single
> "catch all" or "multidrop" mailbox on the ISP.
>
> Users can still access their internal mailboxes from outside through an
OpenVPN connection.? The goal is that only VPN, and perhaps SSH, are
> accessible from the outside.? We do not need to arrange any special SMTP
configuration with the ISP either.
>
> This kind of mail server setup is rather different to the standard
configuration. You do not normally need you own antivirus and spam filter, and
you
> do not need to configure SSL certificates, MX or SPF DNS records. Most ISP
handle that correctly and economically.? Internal e-mail does not leave
> your LAN, and your internal SMTP server is just a relay for the external
ISP SMTP server.
>
> Furthermore, most guides do not explain how to setup an autoresponder
("I am on holiday until xxx") so that users can enable theirs with the
mouse.
> Editing configuration files over SSH is not really an option for normal
users. This detail is important because it could be the only thing I need
> above standard e-mail. Further groupware features can be seen as nice but
ultimately unnecessary luxury, and a basic shared calendar can be
> accomplished with a separate server like https://radicale.org/ and a
calendar client like one built into Thunderbird. Hopefully, that is all I would
> need for a small business.
>
> Can anyone point me to the kind of guide I need? Failing that, I would need
information or examples about using fetchmail, getmail or similar software
> with Dovecot.? Good or bad experiences from you guys would also help.
>
> Each of those tools has a detailed man page, but there are many options and
ways with different advantages and disadvantages.? I would need a simpler
> guide to get started.
>
> I am aware that there are pre-packaged mail server solutions that would
perhaps bring an easy-to-use autoresponder, but I haven't seen one yet that
> where you could tick a box like "this server is only internal and
collects mail from the ISP server" during installation. Nor have I seen
instructions
> about reconfiguring the mail server for my ISP mail scenario.
>
> I am prepared to learn more and write my own Perl scripts and/or
installation guide, but it would be stupid to waste time if something easy
already
> exists.? After all, the setup I am describing (external ISP mail server +
internal mail server) is not so weird.
>
> Thanks in advance,
>  ?? rdiez

> Why don't you configure all stuff internally and ask your provider to
relay
> the e-mails from and to you via "smart relay"?? You will
communicate only
> via smtp and only with your provider,
 > [...]

When you are a small business or a volunteer-run club or charity, you don't
ask your provider. You have no leverage. You may not even be able to
change provider so easily.

Besides, the way you suggest means opening a SMTP port to the outside world. A
security risk and more work at the firewall etc.

 From what I gathered to date, there should be nothing wrong with collecting
e-mails from a catch-all/multidrop POP3/IMAP4 mailbox, so I will carry on
pursuing this method.

Regards,
   rdiez

> Besides, the way you suggest means opening a SMTP port to the outside 
world. A security risk and more work at the firewall etc.

You can just allow some ip addresses of your provider to connect, not? 
Nothing outside world.

> When you are a small business or a volunteer-run club or charity, you 
don't ask your provider. 
 > You have no leverage. You may not even be able to change provider so 
easily.

Just ask, I will bet they do it. They do not need to configure that much 
even I think. By default smtp servers are queueing mail for down hosts.

On 10/26/20 4:16 PM, R. Diez wrote:
>
>> Why don't you configure all stuff internally and ask your provider
to
>> relay
>> the e-mails from and to you via "smart relay"?? You will
communicate
>> only via smtp and only with your provider,
> > [...]
>
> When you are a small business or a volunteer-run club or charity, you 
> don't ask your provider. You have no leverage. You may not even be 
> able to change provider so easily.
>
> Besides, the way you suggest means opening a SMTP port to the outside 
> world. A security risk and more work at the firewall etc.
>
> From what I gathered to date, there should be nothing wrong with 
> collecting e-mails from a catch-all/multidrop POP3/IMAP4 mailbox, so I 
> will carry on pursuing this method.
>
> Regards,
> ? rdiez
You will open the smtp port only to your provider.? The provider will 
receive mails for your domain and will send your mails for outside 
world. He can relay? them to you on an arbitrary port you can open only 
for that server.? You may have right you can't ask him this kind of 
setup but if they already run an e-mail server ( and most of them 
actually do that) it is not such a big effort to add two lines in their 
server config, it cost nothing to? ask :) That will allow you to run a 
complete mail suite almost as in the "real world".

Your approach is ok but is more complicated. That's why I suggested this 
setup, which is simplest but indeed need a little help from your 
provider ( for no matter which provider, in fact).

On 10/26/20 4:16 PM, R. Diez wrote:
>
>> Why don't you configure all stuff internally and ask your provider
to
>> relay
>> the e-mails from and to you via "smart relay"?? You will
communicate
>> only via smtp and only with your provider,
> > [...]
>
> When you are a small business or a volunteer-run club or charity, you 
> don't ask your provider. You have no leverage. You may not even be 
> able to change provider so easily.
>
> Besides, the way you suggest means opening a SMTP port to the outside 
> world. A security risk and more work at the firewall etc.
>
> From what I gathered to date, there should be nothing wrong with 
> collecting e-mails from a catch-all/multidrop POP3/IMAP4 mailbox, so I 
> will carry on pursuing this method.
>
> Regards,
> ? rdiez
>