Thank you Eric,
Actually it is not a live system right now, but do I have to back up of Postfix Configuration? I have already installed Virtualmin through webmin, where can I find install.sh?
Thanks
So, the uninstall option only pulls out Virtualmin specific packages…it won’t clean up a botched Postfix configuration or start it from scratch. To do that, you’d want to remove the Postfix package entirely (apt will probably want to install sendmail, if you’d removed it at any point in this process), using whatever option tells the package manager to kill the config files as well (if needed, as it is on Debian/Ubuntu), and then let the install script reinstall it and configure it for you.
The -u|–uninstall option is somewhat simplistic, and can’t do much to clean up anything that got botched outside of the stuff that the install mode usually handles–so, if you turned off the virtual maps file, it’ll get fixed, but if you did something to logging, or the various recipient/sender maps, or whatever, they would remain the same after an uninstall/reinstall cycle.
It is an imprecise art, dealing with so many packages and so much configuration. The next major release of the install script (written in Perl) will be quite a bit smarter, and will be able to deal with numerous contingencies that the shell script can’t even think about. There will also be a bit more use of meta-packages (package groups in yum, and I’m not sure what yet in apt-get, but I guess it has something similar) rather than hard dependencies.
Aha!
That explain a lot, actually.
The best way to install Virtualmin is using Joe’s really nifty install.sh script – which handles setting up a lot of stuff on the server that won’t otherwise be setup correctly.
You’ll also see the theme designed specifically for Virtualmin, and a lot of things may make more sense once, as you’ll begin to see all the Virtualmin options not available to you using the Webmin theme.
You can get the install.sh script here:
http://webmin.com/vinstall.html
When you run that, it’ll set up all those goodies for you.
You don’t have to back up your Postfix configuration, only if you have something now that you want to be able to get at later 
-Eric
I have decided to uninstall virtualmin and all virtualserver and reinstall them again? where is install.sh related to this matter?
please guide me.
OK, I am trying to uninstall it first and reinstall it again!
Sorry, where should I run it. When I execute: "./install.sh -u" I get the following messages:
error: package virtualmin-base is not installed
error: package wbm-virtual-server is not installed
error: package wbm-virtualmin-htpasswd is not installed
error: package wbm-virtualmin-dav is not installed
error: package wbm-virtualmin-mailman is not installed
error: package wbm-virtualmin-awstats is not installed
error: package wbm-virtualmin-svn is not installed
error: package wbt-virtual-server-theme is not installed
error: package ust-virtual-server-theme is not installed
error: package awstats is not installed
Done. There's probably quite a bit of related packages and such left behind
but all of the Virtualmin-specific packages have been removed.
Whatcan I do?
It has mentioned here(http://webmin.com/vinstall.html) that installer should not execute at system currently running Webmin! As you know mine has Webmin running. How to deal with this issue?
The point of any warnings about running the install script is that the install script dramatically alters configuration. If you have a production system, things might break, if you run install.sh on it.
Also, if you installed Webmin using odd packages from some source other than ours (either Webmin.com or Virtualmin.com), then there will very, very, very, likely be conflicts in the way things are configured or setup, and the install will fail in possibly subtle (but time-consuming to fix) ways.
So, is this a production system? Is Webmin installed from an odd source, or from a tarball rather than the correct package type for your system? If no on both counts, running install.sh should be fine.
install.sh is most happy on a freshly installed Grade A supported operating system. If the system is not freshly installed (meaning you’ve installed and configured a bunch of other stuff before running install.sh, including, but not limited to Webmin) you’ll just confuse the poor thing and probably break whatever configuration you’ve done (which may also lead to the new configuration not working either). But, there are varying degrees of “not freshly installed”. I have no idea how “not freshly installed” your system is. 
Thank you for your reply.
I have bought the VPS with installed Webmin, I am not aware of odd packages. I think I have to spend some more time on it.
Anyway, I will contact the VPS provider and wait for their answer about od packages. I think it is enough for today.
Thank you for your helps.
Thank you guys!
Reinstalling the Webnmin and Virtualmin did not resolve the problem. However after some research I found how to resolve it. By looking at master.cf file and this line :
-o smtpd_client_restrictions=permit_sasl_authenticate d,reject
This line makes restriction for incoming messages from External STMP server. I have commented this line and Postfix is working fine. I must note that I found the solution somewhere on the web.
There is another problem, after reinstalling Webmin & VirtualMin the real memory usage is 128/128 and there is no free memory in real memory. Is it a risk to have several sites in this case?
Regards,
Once again the problem came back, Postfix acts as like as SendMail now. It does not send e-mail to some out servers. It brings time out error.
Nov 19 05:46:37 server postfix/smtp[18018]: 1BD1F10F59CB: to=<admin@outsite.com>, relay=mail1.outserver.net[XX.20.XX.193]:25, delay=1358, delays=1187/0.01/0.4/170, dsn=4.0.0, status=deferred (host mail1.outserver.net[XX.20.XX.193] said: 421 planet.outserver.net SMTP incoming data timeout - closing connection. (in reply to end of DATA command))
please help me!
regards
In regards to memory usage - yeah, 128Mb is considered a low memory system. It can be coaxed to work (depending on how much a load you’re expecting it to handle), though you certainly might want to consider getting some more RAM for it.
You might want to look at this guide for Virtualmin on low memory systems:
http://www.virtualmin.com/documentation/id,virtualmin_on_low_memory_systems/
I can’t answer whether it’ll work for your specific case, it depends more on their resource demands, how much traffic, how much email you process – but you could always try it
In regards to the problem you’re seeing in sending email – do you get the “421 incoming data timeout” for any outgoing email you send, or is it just to that one site?
-Eric
Regarding e-mail sending : yes, I get error approximately for all outgoing emails except with yahoo or gmail. (I have sent e-mails to these e-mail addresses yesterday, but now it shows error 421)
Yahoo says:
Nov 19 07:19:48 server postfix/smtp[28000]: 2E6F810F59CB: host d.mx.mail.yahoo.com[66.196.82.7] refused to talk to me: 421 Message from (XX.8.XX.30) temporarily deferred - 4.16.50. Please refer to http://help.yahoo.com/help/us/mail/defer/defer-06.html
but accepts e-mail message by delay. Other sites do not.
please guide me.
Well, the Yahoo message is okay, they’re probably greylisting you, which just means the message will go through later.
I poked around a little bit searching for ideas on what might cause that 421/timeout error, and came up with some interesting possibilities.
I first ran into it here:
http://nepbabu.livejournal.com/16663.html
Which led me to this Postfix FAQ:
(search for: Mail fails consistently with timeout or lost connection)
http://www.postfix.org/faq.html
Which would explain why you’re seeing the issue in both Sendmail and Postfix. So, try finding the sysctl syntax to “disable path MTU discovery”, and that might just do the trick
-Eric
Thank you, but please excuse me that I am really confused.
My problem is the same as "Matt Armstrong" in http://nepbabu.livejournal.com/16663.html. But how do I drop my routers MTU to 1492 promptly (as "Matt Armstrong" noted he has resolved the problem by this way)? I do not know what is it?
Please guide me.
There are two Configuration Items contain "mtu" when I type sysctl -A :
1)net.ipv4.ip_no_pmtu_disc = 0
2)net.ipv4.tcp_mtu_probing = 0
How do I change them?
Routers have a setting in them called an “MTU”. He’s just saying he made sure they were set no higher than 1492.
If you colocate your box, that may be a setting with your ISP/provider.
However, in the Postfix FAQ, it says that a "bandaid" for the problem is to use the "sysctl" command to "disable path MTU discovery" on your server.
I don’t know the syntax off the top of my head, but I’m sure a Google search will lead you to how to do that.
-Eric
Thank you, I decide to send first item, but when I try to execute the below command :
echo "1" >/proc/sys/net/ipv4/ip_no_pmtu_disc
it says :
-bash: /proc/sys/net/ipv4/ip_no_pmtu_disc: Operation not permitted
Do you know why do I see this, I am logged in as root!
regards,
Anyway, thank you guys!
It is a BIG CLUE, I keep my GOOGLING to find a way!
THANKS
Try running:
sysctl -w net.ipv4.ip_no_pmtu_disc = 1