Migrating IMAP Mailboxes to Exchange Online?

A few observations that are NOT mentioned n the documentation: https://learn.microsoft.com/en-us/exchange/mailbox-migration/migrating-imap-mailboxes/migrate-other-types-of-imap-mailboxes

1. The destination mailbox is first in the file (it does actually state this later on in the how to if you RTFM).
2. Easiest to just do one mailbox per migration batch. (When there is an error, is easiest to redo individuals and remember where you got up to).
3. You CANNOT have two batches running (or even scheduled to run), with the same mailbox destination.

Why would you even have this situation you may ask..

Let's say there are some historic mailboxes at the old host that are ging to be abandoned.. why not migrate those all into one [free] Shared mailbox, just in case they are needed?

You would think you could just specify a csv like this:

history@newhost.com, furst@oldimaphost.com,password124

history@newhost.com, shecond@oldimaphost.com,password124

history@newhost.com, thurd@oldimaphost.com,password124

No such luck, each one needs to be run on its own, completed and then deleted before the next one can be started!

One further undocumented issue - can a migration be done to a Shared mailbox (so not requiring a license)?

Not sure, because I added it as a licensed user first, before I realised the issue above...

I might remove the user's license now the job done, and leave it as a shared mailbox = which generously currently allows a 50GB mailbox on the house!

Also. after each migration, it may be to drag the content into a new subfolder per person, so as not to have have a hug mixed up Inbox.

Which would be ideal if the webmail page allowed this. Drag an drop worked well for folders, but select all items in the Inbox, and they simply would not drag or (right-click Move) to another folder.

Oh well. No-one is ever going to look in it anyway. And Search is your friend.

Oh, and don't forget to complete the batches BEFORE you change the MX records.. although it does still work if you don't (ask me how I know)

Oh - here is the AI take on things:

To migrate multiple IMAP mailboxes into a single shared mailbox in Exchange Online, you generally need to migrate each source account into a temporary licensed user mailbox first, then merge or move the data into the target shared mailbox. Microsoft’s native IMAP migration tool is designed for 1-to-1 mailbox transfers; it does not natively "merge" multiple source accounts into one destination in a single step. 

Recommended Migration Workflow

1. Prepare the Target Shared Mailbox: Create the shared mailbox in the Exchange Admin Center (EAC) and ensure it has a large enough storage limit (default is 50 GB for unlicenced shared mailboxes).
2. Create Temporary User Mailboxes: For each IMAP account you want to migrate, create a corresponding user in Microsoft 365 and assign a temporary license.
3. Run the IMAP Migration

Tired of waiting for Microsoft's Consumer Extended Security Updates?

I've been promising customers that the option to take up the “Consumer ESU” is coming soooon.. but I've only seen it pop up once If you'd rather pay - here is where you do to get it https://apps.microsoft.com/detail/9n87tz9kbj74

Microsoft now offers you a lower level upgrade from the free Personal account to allow 100GB storage and an online email box - all for $3 per month. That's pretty good! Go basic

Outlook (again!) GWSO issues with existing profiles.. after upgrading from Office 2016 (32 bit) to O365 64

The GWSO tool is great. But if you have an existing profile that uses this, then when you come to reinstall it, you get the following weird cryptic message: A profile for Google Workspace sync (named 'temp') already exists - you're all set! If you need to create a new profile, please use the 'Setup a Google Workspace Sync user' option from the Start menu. This made no sense (as I had deleted the current gwso profiles I saw in Control Panel Mail profiles..) until I looked in the Windows Start menu and lo and behold there was a new entry to do just that. This quickly ran through the credential prompts, created the new gwso profile as it said it would!

Repopulate the autocomplete emails in a new Outlook profile or installation

 In the old days, the nk2 file was the go to file to get things working again when the old one was no more due to a new Outlook profile  or a new PC..

Later, it was the Autocomplete List cache stored in the hidden folder somewhere in your users' profile folder structure. This was easy enough to copy over to the new user's autocomplete - overwriting the new empty file but using the new filename. (Outlook needs to be closed while you do this)

This list is limited to 1000 by the way, so another reason not to go relying on it to remember all your customers' email address!

However, if you are using Google's sync tool, this appears not to apply!

So to get around this, the trick is to export the contacts t a PST, then import them to the new profile.

That, however does NOT restore the autocomplete that the user is expecting.

The trick is to simply compose  new email, and populate the to or cc or bcc filed with AL the contacts and let it resolve. But you DON'T need to send it, jus cancel out and delete this draft.

From now on the autocomplete will know all the "new" addresses, so the user can carry on as they were addressing emails by typing just the first letter or two, and getting the autocomplete suggestions they were expecting.

In a new email, select ALL (Click and drag down to the bottom)

Let the addresses Resolve, Escape out without sending or saving

Job done!

Moving cached IMAP folders into OnMyMac when offline

If you try and move messages or folders in the IMAp folders of an account that is not online - you will be thwarted!

BUT if you take a copy of the files as shown here, and then re import them into your mail account, you can then safely point to another imap server and not lose all your cached content that would otherwise disappear!

Step 1 Create a copy of the folder that matches the list of mailboxes you need..
~/Library/Mail/Vx/RANDOM-NUMBER
I copied while Mail was open with no issue!




Step 2
From File choose Import and choose Apple Mail format.



The Imports create an Import folder each time you attempt it in the On my mac section.

Step 3
Then simply drag and drop the content of each folder, (or entire folders) up into either the On my Mac section,
Step3a or MOVE the folders into the IMAP folders area to upload to the new server... although I couldn't get this actually to copy so left this step out!
It may be that you need to create the empty folders on the IMAP are and then drag the mail items into each one ?


In a  similar vain - see also https://www.macworld.com/article/3272250/how-to-recover-a-mail-folder-from-time-machine-in-macos.html which details much the same procedure but from a  mailbox restored using Time machine.

Autocomplete and Recently Used Contacts in Office 2016 2019

Occasionally a new cache file is built for some reason and the old one abandoned by Outlook.

Simply rename the current one in use (you can tell by the date), and then copy over the slightly older one (but it will have a large file size compared to the new one in use).

Restart Outlook – and Voila – it starts working again.

Now if we could only get the users to add these emails into their address book – or get Outlook to do that automatically!

 Kudos to this article for hints on the autocomplete file and overwriting it https://kb.intermedia.net/Article/1894

When its working - the user is greeted by these happy (full) dialog boxes :)

When I stops working (possibly due to the G Sync tool?) the user has no entries in these dropdown boxes and feels LOST!

To fix it, I simply copy over an older (but larger Stream_Autocomplete_xxx.dat file. In this case I could have used the one ending in F82, but instead chose to use a slightly older but larger version I put away  in May in case this happened again - which it did!!