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

> 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.

>> 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.

Yes, you all want me to open ports. I'm sorry guys, but I won't budge:

1) Opening a port means reconfiguring the firewall. You may find it funny, but
some non-profits have no firewall, just a standard ADSL router. The
ones that the telecom company provides often has no IP filtering abilities.

2) I will not expose an SMTP server to the outside word. I will not install in,
or advise to, a small business a piece of software that craves for
attention (patch me, patch me!).

3) Of course I can ask the current ISP. And they may comply. But how about the
next one?

4) Of course I can filter my provider's IP in some Linux firewall. But then
the provider will change its setup and won't tell me. Or I will not have
time to modify the configuration. Or the next person will not have time just
this week.

5) There is really no need. A multidrop / "catch all" mailbox should
work fine. And it is a pretty standard feature in all ISPs I know of. Many
people
are using this kind of setup.

It's only that it is hard to learn, because there is no single, complete
tutorial for this kind setup that I have found yet. But I am collecting more
info, so maybe I will end up writing one myself.

6) Even if it does not make sense, I want to learn how to do it. Just for fun.

You probably mean it well, but if that is all the advice you can give me, it is
not really helping!

I really still think that you should not advise other people to expose servers
on the Internet if there is not really a _very_ good reason, especially
for small businesses or volunteer-driven clubs or charities. The only good
reasons I found yet are for SSH and OpenVPN. Anything else is a "no
go" in
this kind of environment.

Regards,
   rdiez

> Yes, you all want me to open ports. I'm sorry guys, but I won't 
budge:
 > 1) Opening a port means reconfiguring the firewall. You may find it 
funny, but some non-profits have no firewall, just a standard ADSL 
router. The ones that the telecom company provides often has no IP 
filtering abilities.

Read your router manual, you can easily only port forward from a single 
or multiple ips to your local
> 2) I will not expose an SMTP server to the outside word. I will not 
install in, or advise to, a small business a piece of software that 
craves for attention 

The problem is your knowledge is limited, and therefore draw incorrect 
conclusions. So maybe try and find someone that has more knowledge in 
your group, or ask around in your charity.
> 3) Of course I can ask the current ISP. And they may comply. But how 
about the next one?

What next one? You should stick with your ISP for years, I have.
> 4) Of course I can filter my provider's IP in some Linux firewall. But 
then the provider will change its setup and won't tell me. Or I will not 
have time to modify the configuration. Or the next person will not have 
time just this week.

These things do not change. I did not change my mail ip's the last 10 
years or so. I guess only 'hillbillies' that hop around from supplier to
supplier to cut a few dollars a month do this.