Month: June 2021

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Winmail.dat attachment from Outlook. The definitive guide

You use Outlook and send emails with attachments. A recipient of an email tells you that he cannot read the attachment: instead of the attachment there is a file named winmail.dat that he cannot open. The recipient of your email is probably not using Outlook but another email client. It is interesting that if you send an email to another recipient who uses the same email client as the first, same version, he can see and read the attachment correctly.

The first consideration is that the problem “is in you” and not your mail recipients. You need to fix the problem on your Outlook.

Solution 1: send emails as Html

For the first solution you will find hundreds of articles on the internet, we report it here for completeness. You need to set Outlook to send emails in HTML format. In Outlook:

File -> Options

Select “Mail” on the left. You have to make 2 variations.

  1. Under the Compose messages section, change the “Compose messages in this format” dropdown box to HTML
  2. In the “When sending messages in Rich Text format to Internet recipients”, ensure you select either Convert to HTML format

Restart Outlook

Outlook from several versions already has these default settings, so you didn’t need to make these changes. In fact, if that were the problem, it would not explain how some of your recipients are successfully receiving attachments. You haven’t solved the problem.

The definitive solution. The problem of self-completion

If you have correctly configured Outlook as above, here is the definitive solution. The problem is in the auto-completion of the email address. The recipients of your emails who have this problem are surely in memory in the Outlook auto-completion. Auto-completion is that function that is activated while you write the email address in a new email: while you type the recipient’s address, a drop-down menu appears showing the last used addresses. If you use the proposed address, your recipient will receive the winmail.dat file.

If, on the other hand, you write the email address without selecting the address proposed by the auto-completion, your recipient will receive the right attachment.

Let’s recap. The winmail.dat problem affects only some of your recipients; they are recipients who do not use Outlook and have the e-mail address stored in the Outlook memory which appears with auto-completion.

Documents

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Migrate IMAP mailboxes to Microsoft 365 – Office 365 – Exchange online

Here are the steps required in sequence to migrate an IMAP domain to Exchange Online.

  1. Add the domain to your Microsoft 365 tenant. You don’t have to complete the mail server setup.
  2. Add domain users to Microsoft 365. Each user must have a Microsoft 365 Business Basic, Standard, or Premium license
  3. Prepare the csv file for migration, separated by commas. In the first line put EmailAddress, UserName, Password. In the following lines the data: “EmailAddress is the Microsoft account,” UserName “is the imap server account and” Password “is the imap server password

example of csv

EmailAddress,UserName,Password
terrya@contoso.edu,contoso\terry.adams,1091990
annb@contoso.edu,contoso\ann.beebe,2111991
paulc@contoso.edu,contoso\paul.cannon,3281986
  1. Log in as an administrator in Microsoft 365 and go to the Exchange admin center. (Note: this guide is for the “classic” Exchange administration interface. Select “recipients” on the left; select “migration” at the top.
  2. At the center of the page there is a button with three dots: …. Selecting it, the endpoint is inserted, that is the Imap source server. In the next window add the new endpoint (IMAP).
  3. Create a new migration. launch the migration
  4. once the migration is complete, in the tenant, you can finish configuring the domain for what concerns the mail server, following the instructions on the tenant and changing your dns

The Rules of Migration

You can put all users in a migration. When a migration ends in error, you can delete a user from it and put the same user in another migration. You can have multiple migrations at the same time but the same user cannot exist in more than one migration. Migration can exist for up to 60 days.

It is not a migration

In reality, Microsoft does a more sophisticated operation than a “trivial” migration: it makes a sync. Synchronize entire imap mailbox to Exchange mailbox in one direction (from imap to exchange). It is sophisticated but less effective than a normal migration: it is not in real time but after 24/30 hours. So if you want to replace the mail server, users would lose at least 24 hours of email.

Configuring perspectives

On Outlook clients, you can add the new Exchange account online. It will be the same as the old mailbox, but will be managed by Exchange. For a while you will then have 2 mailboxes that manage the same mail but on different servers: one is the old imap server, the other one the new Exchange server. When the migration is finished and you have also moved the mx records on the dns, you can delete the old mailbox. Before doing this, however, you must also memorize the contacts and the calendar from the “old” to the “new”:

Contacts: select all contacts, right click, select “move” and then “copy to folder …”, Exchange mailbox contacts.

Calendar: To move appointments between 2 calendars: both calendars and drag appointments from old to new.

Problems in migration

If you have any problem you can investigate using PowerShell. First install ExchangeOnlineManagement.

Connect to the tenant:

Connect-ExchangeOnline -UserPrincipalName <your Admin Username>

The password request screen appears.

List of all endpoints in the tenant

get-migrationendpoint|FL

endpoint test

Test-MigrationServerAvailability -Endpoint <Identity of the endpoint from above>

view sync configuration of single user

Get-SyncRequest -Mailbox  <user>

esport migration result for a user

Get-MigrationUserStatistics <user> -IncludeSkippedItems -IncludeReport 
-DiagnosticInfo "showtimeslots, showtimeline, 
verbose" | Export-Clixml C:\temp\MigMyUser.xml

Exchange mailboxes have a 35MB limit. If you have to move something bigger during the migration you have to change this limit.

Set-Mailbox -Identity <user> -MaxReceiveSize 150MB

Documentation:

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Outlook for Exchange online: Change the default address book

Exchange online Outlook accounts has the Global Address List (GAL), as a default address book: the one that contains corporate accounts. To set the user’s address book (conatcts) as default, synchronized on Outlook online, you need to:

  1. open Outlook
  2. at the top of the main page there is an icon-button “Address Book”.
  3. In the window that appears select “tools – options”.
  4. select “Start with contact folder”
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Remove Thunderbird from default email client on Windows

Scenario

Even though Outlook is set as the default email client in Windows, when you use that program’s “Send as email” function it brings out a Thunderbird dialog box instead of Outlook.

Solution

Open regedit. (‘Start’ > Run > type regedit)

Check registry key: HKEY_CURRENT_USER\Software\Clients\Mail

right side double click on ‘Default’ Enter Microsoft Outlook in ‘Value Data’

Windows 10 may have some variants

  1. HKEY_CURRENT_USER\Software\Clients\Mailto
  2. HKEY_CLASSES_ROOT\mailto\shell\open\command