Are your Gmail messages not getting delivered in Google Workspace? Try any of these fixes to get the issue resolved in minutes:
Clear Browser Data
Open your browser.
Click the three dots (top right corner).
Select Settings from the list.
Click the three horizontal lines, and select “Privacy and security.”
Select “Delete browsing data.” Then tick the boxes for Cookies and other site data, as well as cached images and files.
Click “More,” then select the time range as “All Time.”
After that, click “Delete data.”
Close and restart the browser.
Sign back into your account and try sending the email again.
Disable Browser Extensions
Open any web browser (e.g., Chrome).
Click the three dots (top-right corner).
Go to Extensions > Manage Extensions.
A list of installed browser extensions and add-ons will appear.
Find enabled extensions and turn off the toggle switch next to each extension to disable it.
Close the browser and reopen it.
Sign in to your account and try to send the message again.
If the emails are sent successfully, turn on the extensions one at a time to find the one causing the issue.
Once the problem extension is found, click Remove to delete it.
Sign Out /Sign In Your Gmail Account
Open Gmail in your browser.
Select your profile icon from the top-right side of the screen.
Select “Sign out.”
Close all open tabs and windows.
Make sure the browser is not open.
Launch the browser again, and go to gmail.com.
Enter your email credentials.
Log in again. This creates a fresh session with Gmail servers.
Click “Compose” and send a test email.
Click the Send button.
Source:- Fix Gmail Not Sending Emails in Google Workspace