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Migrate from Imail 11.03 to Postfix

Hello Experts!

We'd like to migrate from imail 11.03 to postfix. What the best way to achieve this with minimal user interruption?

Thank you.
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Bud DurlandDirector of IT
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Commented:
What type of client access will you be configuring (IMAP/POP/Web)?  What are you looking to achieve by migrating to PostFix?

Author

Commented:
Hello Bud. We will be configuring POP. We manage email domains for several clients... Spammers have been using us as a relay to send massive amounts of spam. We've configured Imail to deliver mail only to our managed domains; but, spam continues to be relayed to external accounts. We've done everything possible in Imail to block this spammer to no avail. We are hoping postfix may improve security.
Bud DurlandDirector of IT
BRONZE EXPERT

Commented:
It sounds like one of your client's e-mail accounts is compromised; unless you force a password change during the switch to PostFix, you won't solve the spam problem.  iMail used to have excellent logging of authenicated SMTP sessions -- I suspect the answer is there.

Author

Commented:
Hi Bud. The spam is coming from @aol and @gmail accounts... Not a client account.
Bud DurlandDirector of IT
BRONZE EXPERT

Commented:
@aol and @gmail may reflect the address in the body of the e-mail, but when the spammer connects to your server, they have to authenticate with an e-maill address for one of the users you support.  This authentication e-mail does NOT have to be a domain match for e-mail being sent.

For example, if I administered the server for 'acme.com', I could send e-mail that looks like it is from 'fred@bedrock.com', but to do so I have to authenticate to the server as 'roadrunner@acme.com'.  Since I authenticated as an 'acme.com' address, the server will allow the relay of the message.

Author

Commented:
Thanks greatly for your help Bud. I'm still not sure this is the case though. Because, wouldn't we see them logging in in the Imail log file? We don't see anyone from any of our accounts making that connection.
Bud DurlandDirector of IT
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Commented:
I haven't used iMail a couple years now, so my memory may be fuzzy, but I seem to recall that you may have to configure what entries iMail should make in the log.  Specifically, you would want to log SMTP Authentication.  

Of course, I'm making the presumption that your SMTP relay option is set to "Only allow relay for authenticated users" or similar

I looked here: http://docs.ipswitch.com/_Messaging/IMailServer/v11/GettingStarted/index.htm

searched for "relay" and found this excerpt:

For secure data communication, SMTP Authentication lets you verify each user who attempts to send mail through your mail server, as long as SMTP Authentication is enabled on the IMail Server. Users need to set their mail clients to do an SMTP login; for example, in Microsoft Outlook on the Tools > Accounts > Mail > Properties > Servers tab select the option My outgoing mail server requires authentication.

SMTP Authentication is used in the following cases:

If you use the No mail relay option for SMTP relay.
If you use the Relay mail for (Addresses) option, SMTP Authentication enables users who send from IP addresses that you do not list; for example, users who are traveling and do not have a static IP address.

Author

Commented:
I greatly appreciate your help Bud. Still, I need advice on migrating from imail 11.03 to postfix. What the best way to achieve this with minimal user interruption?
Bud DurlandDirector of IT
BRONZE EXPERT

Commented:
We've kinda circled back to my original post -- what will you be installing beside PostFix to handle the clients?  PostFix is a message transfer agent (MTA).  It knows how to deliver messages from one mail server to another, and how to accept messages for a domain and store them in a mailbox.  The installations I've seen then have some other software to handle client communication (via IMAP or POP) with the mail box; PostFix does not do that.

Author

Commented:
Bud, I want to thank you again for your assistance. Here is our planned config. Ubuntu + Postfix + Courier IMAP + MySQL + Amavisd-new + SpamAssassin + ClamAV + SASL + TLS + SquirrelMail/Roundcube + Postgrey
Director of IT
BRONZE EXPERT
Commented:
Ok.  You will likely have to be prepared to re-create all your user accounts by hand.  Sorry, I'm really not super familiar with linux, so I don't know of any easier way to do it.  There may be a way to export your current iMail users to a plain text file, then update the text file with passwords and import it into your system, but I am not familiar enough to know.

However, given the above config, the general plan would be:

Set up the new Linux server with Postfix & friends, with a temporary host name.  Use that name to test mail flow from inside your network.

Once the Linux testing is done, change the iMail host's IP address & host name to some temporary values.

Rename the Linux host to it's production name & IP address (there may be some PostFix related config files to edit), then bring it up.

Change your outside DNS server's MX records to point to the new Linux server, if necessary

At this point, NEW mail will come into the new server, and should be visible to users.  They, of course, will immediately begin to complain about old mail, which we will solve in the next step.

Google 'IMAPCOPY', or visit http://home.arcor.de/armin.diehl/imapcopy/imapcopy.html

IMAPCOPY is a utility that uses the IMAP protocol to copy ALL the messages stored on an account on one server to an account on a different server.  To make it work, you need everyone's mail login name and password.  I've used it a couple times and can tell you it works pretty well. Read the help (IMAPCOPY -h) carefully.  I recommend running it in "create folders only" mode until it goes error-free, then run to copy messages.

Author

Commented:
Thank you Bud you've been a tremendous help.

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