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Change New Exchange Server - Error pear_error: message="NO, Server Unavailable.

Posted: 11 Sep 2019, 13:28
by NandoNaldo
Hello,

We need to migrate from one exchange server to the other one. I have changed the IP of the new exchange server and the user used to logon but when i try to do complete test i have:

Mailbox: Email test pershkrim
Location: Attempt login
[pear_error: message="NO, Server Unavailable. 15" code=0 mode=return level=notice prefix="" info=""]

Please could you help me ?

Re: Change New Exchange Server - Error pear_error: message="NO, Server Unavailable.

Posted: 12 Sep 2019, 18:24
by TerranceM
I've come across this issue twice with 2 different exchange 2013 farms while setting up IMAP to use IMAPSync to migrate mail. The issue only happened when accessing 1 folder with lots of mail messages. A simple test is to use OpenSSL to verify the issue like:

openssl s_client -quiet -crlf -connect mail.domain.com:993
A01 login domain/user password
A02 LIST "" *
A03 SELECT "problem folder"

IMAP will return: A03 NO Server Unavailable. 15

After change lots of IMAP settings, the resolution is to enable IMAP protocol logging. It was previously (by default) disabled and this issue would happen. We disabled it again and the problem returned for the same mailbox. Re-enabled logging en voila works.

Set-ImapSettings -Server <server-name> -ProtocolLogEnabled $true

Hope this helps!

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Terrance