If you haven’t yet, review the Google Workspace Migrate best practices first.
Before you migrate content from Microsoft Exchange, review the following points for email, calendar resources, and other data.
Email messages | Gmail labels | Email filters | Calendar data | Calendar resources | Other types of data
Email messages
Email forwarding |
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To avoid duplicates and errors, email messages are checked to make sure they don’t already exist in the target mailbox.
If you use email forwarding and enable the Accelerate old messages setting, set the Insert Before Date field to the day before forwarding was turned on to reduce the risk of data duplication. For details, go to Migrate Exchange content. |
Deleted email messages |
Deleted messages go to Trash in Gmail. Per Gmail guidelines, items in Trash are deleted after 30 days. For details, go to Delete or recover deleted Gmail messages. |
Large attachments |
During a migration, email attachments over 25 MB are added to Google Drive. A link to the attachment is added to the migrated message.
You can configure the size threshold and Drive folder name for these attachments in the settings template. For details, go to About Exchange settings template options. |
Date headers in email |
If an email has a date header that doesn't conform to the RFC-2822 standard, you will see the migration date, not the original message date, in the target mailbox. |
Difference in the total amount of email messages |
Due to the difference between folders in Exchange and labels in Gmail, the number of email messages in the source account might exceed the number of messages migrated to Gmail. In Exchange, when you assign a message to more than one folder, the message is duplicated. Following a migration, the duplications are removed in Gmail and different labels are applied instead. To verify that all messages have been migrated, check the logs for any errors. For details, go to Monitor migration progress. To troubleshoot further, go to Missing email messages. |
Migrating messages to Google Groups |
When viewed in Groups, migrated email messages appear as read by the user who sent them. For other group members, the messages appear as unread. |
Links in email messages |
Gmail scans migrated email messages for security and threat issues and occasionally crawls links in the body of email messages.
To avoid this issue and modestly increase migration performance, you can use the Accelerate old messages option in your settings template. Before you do, review how it works. For details, go to Migrate Exchange content. |
Email messages sent by users to themselves |
If Exchange users sent a message to themselves and the message is in the Sent folder, following a migration:
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Gmail labels
Migrating folders to labels |
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Email folders and subfolders are migrated as labels and sublabels in Gmail. Gmail supports up to 5,000 labels in a user mailbox. Labels have the same name and hierarchy as folders, except as indicated below. Note the following points:
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Folder names that contain special characters or multiple sequential spaces |
After a migration, folder names that contain the following characters or spaces don’t directly match label names on the target account:
On the labels created from the folders:
During a migration, folders that have the same name (following any adjustments) merge into one label. For example, because special characters are removed, the folders Financial1 and Financial1^ merge under the label name Financial1. |
Label colors |
Only standard label colors are supported. Any non-standard colors for categories on the source account don't migrate as labels.
If you get an error, remove the custom colors from categories in the source account and try again. For details about standard label colors, go to Gmail API: Color. |
Email filters
Calendar data
API limits |
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If you're running a large migration (1,000+ calendars), you might reach the Google Calendar API daily limit and see 403 errors. You can request an increase to the query-per-minute limit for the Calendar API:
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Primary to secondary calendar migration |
To map a primary calendar to a secondary calendar on your target domain, use a GCalendar entry in your mapping.
Your mapping should include:
Important: If the mapping is misconfigured, events might be migrated to the target user's primary calendar. Check your mapping carefully before proceeding. |
Use an identity mapping |
Use an identity mapping to:
For details, go to Create & manage an identity mapping. |
Calendar resources
Steps to migrate resources & event associations |
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Auto-accepted meetings |
If the calendar resource is set to Auto-accept meetings that do not conflict (the default) and conflicting bookings are migrated, the meeting organizer gets an email for each declined invitation. The super administrator account used to migrate the resource also receives an email. For details on using super admin accounts to migrate calendar resource events, go to Migrate using super administrator accounts.
To use content compliance rules to deliver these messages to email quarantines, go to Set up rules for advanced email content filtering. |
Migrate using super administrator accounts |
By default, Google Workspace Migrate uses all super administrator accounts to write calendar resource events to the target domain. Using super admin accounts increases migration speed and reduces the risk of quota issues.
Note the following points:
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Resources created after January 21, 2020 |
Calendar resources created after January 21, 2020, might show unexpected Location Not Found errors during a migration. To resolve these errors, upgrade to Google Workspace Migrate version 2.1.26.0 or later. For details, see Upgrade the software. |
Other types of data
Groups |
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For Google Groups, you must create groups in the target account first. Groups aren't automatically created by the migration process. When migrating groups:
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Exchange contact notes |
Unlike Google Workspace, there is no limit to the notes size for an Exchange contact. When contact notes are migrated, large notes might be truncated in Google Workspace. |
Migrating large numbers of contacts |
Google Contacts supports up to 25,000 personal contacts for each user. Before you migrate, make sure your users have fewer than 25,000 personal contacts in Exchange. |
Tasks |
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Next step
Now it's time to set up an Exchange connection. To get started, see Set up Exchange connection.
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