Hi, @SteveCRF
Based on your description, I understand that you are experiencing a problem with a user who is not receiving third-party verification code emails.
Your testing will also show that the issue is focused on the affected user.
Here are some suggestions you can try:
1.Message Trace will record the status of each email. Again, make sure that the mail server is receiving the message, so that you can better narrow it down.
You can use EAC and set the appropriate time frame or use Power Shell.
Get-MessageTrace
2.Check the mail filters and rules in the user's mailbox to make sure that there are no filters or rules set up that will block or redirect messages from Canva, such as if you have set up mail forwarding, which could cause messages to be lost or redirected.
3.Whitelist Canva.com or place Canva.com in the Safe Senders list. Also check if Canva.com is included in the Blocked Senders.
4.Last but not least, whether the affected user has recently deleted or modified the email alias, resulting in the third-party service still sending emails to the old email alias, and the third-party service not keeping up with the new email aliases in a timely manner.
As a temporary alternative, you can try changing the email address that accepts the verification code for the user so that it doesn't affect your normal use. While waiting for your further troubleshooting.
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