Best practices in Outlook Mail
When using Outlook Mail with G Suite Sync for Microsoft® Outlook® (GSSMO)...
Place messages here that you want to remove from your Inbox but keep around for reference. (You have 30 gigabytes of storage in the cloud for your personal G Suite account so you won't run out of space!) The Archived folder also contains messages you archive using the Gmail interface, that aren't already in another folder. Learn more about archiving.
Set up mail delegation from Gmail (not Outlook)
You can let an assistant manage your Inbox from Outlook by reading, deleting, and sending mail on your behalf. But you set this up in your Gmail web interface, not using the Delegates tab in Outlook's Options dialog (which isn't available with GSSMO).
Learn to delegate your mail with GSSMO
Use Gmail's Vacation Responder (not Outlook's OOO assistant)
You can set up automatic vacation responses to let people who email you know when you're away from your mail. But you need to do this in your Gmail web interface, not using Outlook's Out of Office feature (which doesn't work with GSSMO).
Learn to use the vacation responder
Set a local Mailbox Size limit:
This is necessary only if you want to store more than 1GB of mail in your local Outlook mailbox. Regardless of your local mailbox size, all your mail is available from your Gmail account in the cloud.
Make G Suite your default account (over any POP or IMAP account):
You can add other mail accounts to your G Suite profile, say, for personal or family-related mail, just as you can with Microsoft® Exchange. Mail sent to a POP3 account appears in your main Inbox along with your G Suite mail, while mail sent to an IMAP account goes into a separate Inbox for that account. Just be sure that your G Suite account is the default account in your profile (otherwise calendar invitations sent to your G Suite account might not end up on your calendar). Do this in Outlook's Tools > Account Settings dialog, on the E-mail tab.
Note that neither your POP nor IMAP mail is synchronized with your G Suite account in the cloud. Nor will calendar invitations sent to your POP or IMAP account appear on your calendar.
Compose HTML mail, not Rich Text:
By default, GSSMO sets your preference for composing mail in HTML format, rather than Rich Text. Don't change it back to Rich Text or messages you send won't be readable.
Find your Sync Issues folder:
GSSMO creates a special Sync Issues folder that tracks synchronization performance. Most of the time you can ignore this folder. But on occasion, your administrator might ask to see its messages to help troubleshoot a problem. The Sync Issues folder is in your Folder List.To see it, go to Outlook Mail and choose Go > Folder List.