Re: dsync replication fails with No space left on device / Out of memory

[@lbutlr]

On 2021 Jul 05, at 02:00, Steven Varco  wrote:
> I then increased the filesystem size and all the problems suddenly vanished.

How large was your tmp before and after the change, out of curiosity?

-- 
-=> 

 <=-

Dovecot book for a newbie

[techlists]

Hi,

Please recommend a Dovecot book for a newbie... I have a fair amount of 
Linux PHP hosting experience - LAMP virtual host configurations.  I'm 
new to BIND, Postfix, and Dovecot.


I'm running Ubuntu 20.04lts.

I have a test server almost working.  Can send but not receive.  Would 
like to understand more.  I'm guessing it is a Zone (MX) / SSL / Client 
configuration issue.


Thanks in advance!!

Re: Dovecot book for a newbie

[Kevin N.]

I am not aware of any Dovecot specific book, but maybe a good starting 
point would be the Dovecot Quick Configuration guide:

https://doc.dovecot.org/configuration_manual/quick_configuration/

For Postfix, a good starting point could be the VIRTUAL_README and 
ADDRESS_CLASS_README pages:

http://www.postfix.org/VIRTUAL_README.html
http://www.postfix.org/ADDRESS_CLASS_README.html

I've also heard good things about "The Book of Postfix". Even though it 
is quite old now, most of the parts/concepts/terminology still apply 
today. Part of it is also available on Google Books.


Setting up a mail server for the first time can be a bit challenging and 
time consuming, but once you get a hold of things, it gets much easier :)


Personally, I would take things step by step and not try to install and 
configure everything all at once.


You could create a local isolated virtual environment with multiple VMs 
(ex: 1 authoritative DNS server for local testdomain1 and testdomain2, 1 
mail server for local testdomain1, 1 mail server for local testdomain2) 
where you could experiment freely until everything works as expected.


That way you are in control of the entire environment and you can easily 
debug any issues. Plus, it can be a good learning experience :)


Once messages can be sent between the local test domains without any 
issues, you could take that configuration and, more or less, apply it to 
your internet facing mail server.



Hi,

Please recommend a Dovecot book for a newbie... I have a fair amount of 
Linux PHP hosting experience - LAMP virtual host configurations.  I'm 
new to BIND, Postfix, and Dovecot.


I'm running Ubuntu 20.04lts.

Can send but not receive.


Assuming everything else is set up correctly, did you check your 
firewall just to make sure that is not blocking incoming connections on 
your SMTP port?




Cheers,

K.

Re: Dovecot book for a newbie

[Kevin N.]

I am not aware of any Dovecot specific book, but maybe a good starting 
point would be the Dovecot Quick Configuration guide:

https://doc.dovecot.org/configuration_manual/quick_configuration/

For Postfix, a good starting point could be the VIRTUAL_README and 
ADDRESS_CLASS_README pages:

http://www.postfix.org/VIRTUAL_README.html
http://www.postfix.org/ADDRESS_CLASS_README.html

I've also heard good things about "The Book of Postfix". Even though it 
is quite old now, most of the parts/concepts/terminology still apply 
today. Part of it is also available on Google Books.


Setting up a mail server for the first time can be a bit challenging and 
time consuming, but once you get a hold of things, it gets much easier :)


Personally, I would take things step by step and not try to install and 
configure everything all at once.


You could create a local isolated virtual environment with multiple VMs 
(ex: 1 authoritative DNS server for local testdomain1 and testdomain2, 1 
mail server for local testdomain1, 1 mail server for local testdomain2) 
where you could experiment freely until everything works as expected.


That way you are in control of the entire environment and you can easily 
debug any issues. Plus, it can be a good learning experience :)


Once messages can be sent between the local test domains without any 
issues, you could take that configuration and, more or less, apply it to 
your internet facing mail server.


> Hi,
>
> Please recommend a Dovecot book for a newbie... I have a fair amount 
of Linux PHP hosting experience - LAMP virtual host configurations.  I'm 
new to BIND, Postfix, and Dovecot.

>
> I'm running Ubuntu 20.04lts.
>
> Can send but not receive.

Assuming everything else is set up correctly, did you check your 
firewall just to make sure that is not blocking incoming connections on 
your SMTP port?




Cheers,

K.

Re: Dovecot book for a newbie

[Richard Doyle]

https://www.amazon.com/Dovecot-POP3-IMAP-servers-enterprises/dp/1534895701


On 7/7/21 10:04 AM, techli...@phpcoderusa.com wrote:
> 
> 
> Hi,
> 
> Please recommend a Dovecot book for a newbie... I have a fair amount of
> Linux PHP hosting experience - LAMP virtual host configurations.  I'm
> new to BIND, Postfix, and Dovecot.
> 
> I'm running Ubuntu 20.04lts.
> 
> I have a test server almost working.  Can send but not receive.  Would
> like to understand more.  I'm guessing it is a Zone (MX) / SSL / Client
> configuration issue.
> 
> Thanks in advance!!
> 

Re: Dovecot book for a newbie

[li...@lazygranch.com]

On Wed, 07 Jul 2021 10:04:06 -0700
techli...@phpcoderusa.com wrote:

> 
> 
> Hi,
> 
> Please recommend a Dovecot book for a newbie... I have a fair amount
> of Linux PHP hosting experience - LAMP virtual host configurations.
> I'm new to BIND, Postfix, and Dovecot.
> 
> I'm running Ubuntu 20.04lts.
> 
> I have a test server almost working.  Can send but not receive.
> Would like to understand more.  I'm guessing it is a Zone (MX) / SSL
> / Client configuration issue.
> 
> Thanks in advance!!
> 

I used this person's blog when I set up my servers. Unfortunately he
only has guides for centos and freebsd but it is worth checking out. I
think the odds of me setting up an email server from just the manuals
would be zero, keyword me. But ubuntu verses centos should just be a
packaging issue.

https://blog.andreev.it/?p=1975

I recall it being correct put not complete regarding postfix. I don't
recall any Dovecot issue. It is 99% there. What I like is the guide
provides a test at each step.

I advise you to start out small and add features later or never. After
being hacked via RoundCube when I used a hosting service I am a firm
believer in keeping the attack surface small. If this is a personal
server (as is mine) I wouldn't even bother with spamassasin. You can
stop much spam simply via Postfix. What this guide lacks is a number of
milters for postfix required for DKIM and DMARC. Also I would set up
the server using "submission" (port 587) since that allows for
geofencing all the email ports other than 25, again presuming this is a
personal server where geofencing would be appropriate.

There are a number of websites that can test your email server. For
instance you wouldn't want to mistakenly be an open relay. They will
also help with verifying all the identification features are proper.
The deal with an email server is you need to look legit because the
world is out to block you. In fact there are some ISPs that will simply
reject your email until you contact them to get "allow listed". Some
like Spectrum will never accept email from some VPS. [Sheer
incompetence.]

Lastly my personal philosophy is to make no element of the email server
programmable via a browser. I do everything via ssh and cli. This makes
life hard for the hackers. 

Re: dsync replication fails with No space left on device / Out of memory

[Steven Varco]

> Am 07.07.2021 um 10:34 schrieb @lbutlr :
> 
> On 2021 Jul 05, at 02:00, Steven Varco  wrote:
>> I then increased the filesystem size and all the problems suddenly vanished.
> 
> How large was your tmp before and after the change, out of curiosity?

Before it was 128 MB which is admittedly quite low. However, usually no 
compontent ever reachs this limit as temporary files are generally quite low in 
size, so I never had a problem with postfix, amavis, dovecot, or even a LAMP 
stack, and therefore I did not expect that in the first place.

After I have extended the /tmp volume to reasonably 1 GB which should be pretty 
fine for the future. :)

best regards,
Steven

Major upgrade of mail server

[Shawn Heisey]

I have a mail server in AWS that is currently running Ubuntu 18.  Every 
time I log in, I am reminded that I can upgrade to Ubuntu 20.


On Ubuntu 18, the dovecot version is 3.3.0-1ubuntu0.3.  On Ubuntu 20, it 
is 2.3.7.2-1ubuntu3.  Many other packages, probably including the mysql 
server, would also be upgraded.


Dovecot and Postfix use a postfixadmin database in mysql for users, and 
postfix is using dovecot-lda to deliver mail.  I am using managesieve 
from dovecot on roundcube webmail.  As far as I know, my own user is the 
only one with sieve scripts actually in use ... and I have a LOT of 
filters/folders for various mailing lists.


I've been a little bit terrified of doing an upgrade, because I do have 
a couple of people using my mail server for real work email and I don't 
want to disrupt them.


I'm writing today to find out what are the likely pain points I might 
encounter when doing this kind of major upgrade, and if there is any 
helpful information that can help me get through those problems.  I'm 
hoping that it will go smoothly and everything just works.


Here's the doveconf -n output:
https://apaste.info/FUgF

If I have been silly enough to include sensitive data from the config, I 
would appreciate a heads up so I know what passwords to change.  I did a 
quick glance and didn't see anything.


Thanks,
Shawn

Re: Major upgrade of mail server

[Plutocrat]

First thing to note is that Ubuntu 18.04 is a Long Term Service release, and 
will be supported until 2023. So no matter how naggy Ubuntu is, you don't 
actually HAVE to upgrade at this point. You may disable the prompt if if 
bothers you: just remove or comment out the relevant file in /etc/update-motd.d/

Now the pressure is off, and you have a bit more time, maybe the best idea 
would be to build and configure a new server using Ubuntu 20, or any other 
distro, and then migrate the data over to it with dsync. That affords you an 
opportunity to test the new config before one final sync, and switching the MX 
records to point to the new server.

If for any reason you are locked into upgrading the current server, the only 
advice I can offer from a recent dovecot migration between an Ubuntu 18 server 
and a Ubuntu 20 server, was that the default SSL settings are considerably 
improved, which meant that a lot of the clients, who were using ancient 
versions of Outlook, were unable to connect. I needed to downgrade the security 
(against my better judgement) in order to let them connect, commenting out the 
line
# ssl_min_protocol=TLSv1.2
so that it defaulted to TLSv1. You might wish to bear this in mind, although 
any modern email client won't have any problems.

Good luck!

P.

On 08/07/2021 09.15, Shawn Heisey wrote:

I have a mail server in AWS that is currently running Ubuntu 18.  Every time I 
log in, I am reminded that I can upgrade to Ubuntu 20.

On Ubuntu 18, the dovecot version is 3.3.0-1ubuntu0.3.  On Ubuntu 20, it is 
2.3.7.2-1ubuntu3.  Many other packages, probably including the mysql server, 
would also be upgraded.

Dovecot and Postfix use a postfixadmin database in mysql for users, and postfix 
is using dovecot-lda to deliver mail.  I am using managesieve from dovecot on 
roundcube webmail.  As far as I know, my own user is the only one with sieve 
scripts actually in use ... and I have a LOT of filters/folders for various 
mailing lists.

I've been a little bit terrified of doing an upgrade, because I do have a 
couple of people using my mail server for real work email and I don't want to 
disrupt them.

I'm writing today to find out what are the likely pain points I might encounter 
when doing this kind of major upgrade, and if there is any helpful information 
that can help me get through those problems.  I'm hoping that it will go 
smoothly and everything just works.

Here's the doveconf -n output:
https://apaste.info/FUgF

If I have been silly enough to include sensitive data from the config, I would 
appreciate a heads up so I know what passwords to change.  I did a quick glance 
and didn't see anything.

Thanks,
Shawn