User Migration Tool, not working
Problem reported by Paul White - Today at 6:41 AM
Submitted
I have client with 10 users that was formally hosting with google workspace (gmail) for their domain. I am in the process of migrating them to my SmarterMail server where hosting will cost much less.  Each user has about 40GB of email.  I have already setup the domain and the 10 years within smartermail. I have not pointed the DNS yet.  Using the built in MIgration tool I am in the process of migrating all their data to smartermail, but the migration fails for some users for unknown reasons.  I did check the IMAP retrival logs and it does show Google timing out the IMAP connections after a few minutes.

Smartermail trys to grab lets say 80 emails from a folder.  It is able to get a limited number of them, before gmail times out the IMAP connection.  Then it waits and trys again later picking up where it left off.  
Of the 6 users I started the migration process only one seems to still be moving data. The other 5 stopped. Here are the logs for one of them.  This user has 40GB of data, the first time only 13 GB were moved before it failed.  I restarted the migration a second time and only 4.22GB were transferred.  

[2026.09.16] 00:48:44.257 [882] [user@domain.com; imap.gmail.com:user@domain.com] Skipping email [2];  Folder: Job 811_;  Size: 6381556 bytes;  UID: 4
[2026.09.16] 00:48:44.258 [882] [user@domain.com; imap.gmail.com:user@domain.com] Downloaded 3 messages from folder "Job 811_"
[2026.09.16] 00:48:44.258 [882] [user@domain.com; imap.gmail.com:user@domain.com] Downloading messages from folder "Job 811_" failed.  Re-trying ...
[2026.09.16] 00:49:25.239 [882] [user@domain.com; imap.gmail.com:user@domain.com] Index was outside the bounds of the array.
[2026.09.16]    at SmarterMail.MailService.RelayServer.Clients.IMAP.丅丝.AuthenticatePlain(IImapAccountV1Readonly account)
[2026.09.16]    at SmarterMail.MailService.RelayServer.MessageRetrieval.丄俌.DownloadMessages(丄俙 trackingFile)
[2026.09.16] 00:49:25.240 [882] [user@domain.com; imap.gmail.com:user@domain.com] Mailbox Migration failed for user@domain.com
[2026.09.16] 00:49:25.241 [882] [user@domain.com; imap.gmail.com:user@domain.com] Processing completed.
[2026.09.16] 00:49:25.246 [882] [user@domain.com; imap.gmail.com:user@domain.com] Sent migration summary message
[2026.09.16] 00:49:25.247 [882] Finished processing for user@domain.com [d67da20e500a4ef9a885e189a54aba86]

Any thoughts on what the problem could be and how to resolve this?
Andrew Barker Replied
Employee Post
The first line in that log snippet should only be added to the log immediately after an exception. Without that exception, there isn't really any way for us to say why the message was skipped.

As for the exception that is in the log lines you provided, it looks like there was some sort of issue when trying to authenticate the connection on a retry. That should only happen if the connection is dropped right in the middle of the authentication process. That could be due to security hardware that monitors your outbound connections or because Gmail's servers dropped the connection for some reason.

Andrew Barker
Lead Software Developer
SmarterTools Inc.
www.smartertools.com 

Reply to Thread

Enter the verification text