There are a few features that G Suite Sync for Microsoft® Outlook® (GSSMO) does not support in Outlook mail. The GSSMO features aren't available in Outlook or might not work as you'd expect.
GSSMO features not in OutlookRecovering deleted items
After emptying your Deleted items folder, you can't use "Recover Deleted Items" in Outlook's Tools menu to get the messages back. (This menu item isn't available.)
You can't share a mailbox folder in Outlook with other users. (Permissions settings aren't available in the folder's Properties dialog.) This is because folders in Outlook map to labels in Gmail, which don't have permission properties.
Public folders aren't available with GSSMO. (They're missing from Outlook's navigation pane.)
GSSMO doesn't allow sending executable file attachments (including executables in compressed attachments) from Outlook or the Gmail interface.
Types of files that can't be sent from Outlook: .ade, .adp, .bat, .chm, .cmd, .com, .cpl, .dll, .exe, .hta, .ins, .isp, .jse, .lib, .mde, .msc, .msg, .msp, .mst, .pif, .scr, .sct, .shb, .sys, .vb, .vbe,.vbs, .vxd, .wsc, .wsf, .wsh
There are also limitations when you send .eml or .msg attachments to Outlook users. For details, see Can't view MSG or EML files.
Delivery receipts aren't generated in Outlook when using GSSMO. If you request a delivery receipt for a message you send from Outlook, you won't receive a response when the message is delivered. Instead, you can request a read receipt.
Email encryption S/MIME isn't supported when you're sending email using GSSMO. As a workaround, S/MIME works if configured using an IMAP connection.
If you're using a Gmail alias and have Treat as alias enabled, the alias will appear in the To or Cc fields when you reply to all in Outlook.
Features in Outlook that are available, but might not work as expectedRead receipts
Read receipts are generated in Outlook with GSSMO. However, your recipient must be using Outlook and must enable read receipts for their profile. In that case, you'll get a response when your message is read.
You can set up automatic vacation responses to let people know when you're away from your mail. But, you need to do this in Gmail, not using Outlook's Out of Office feature (which doesn't work with GSSMO). Learn how to set up an out of office or vacation reply.
You can set up contact delegation in G Suite, so an assistant can access and manage a supervisor's personal contacts. This feature isn't available in Outlook. Instead, you set up contact delegation and access to a supervisor's contacts in G Suite. For details, see Delegate contacts to an assistant.
In Outlook, you can choose "Recall Message" from a sent message's Other Actions menu to try to recall a message you just sent. Unlike Exchange, Gmail can't recall messages. Instead, the recipient receives both the original message, along with a follow-up message saying you wanted to recall the message.
In Outlook, you can send mail marked "Important" or "Low Priority." If you do, these values aren't synchronized with your G Suite account in the cloud and don't show up for other users.