Office 365 Excel set region

We had the same concern. So we created a new site collection specifically for surveys. Then we turned on the setting "Allow both external users who accept sharing invitations and anonymous guest links: in our Tenant, and turned it off for all site collections except the one we will use only for Excel Surveys.

Is there a way to configure a rule in mail that permanently deletes instead of moves to trash?

No, unfortunately there is not. The only rule to delete that is available for Outlook Web App (OWA) is just to move items to the Deleted Items folder. However some alternatives are:

Automatically move files to a folder and permanently delete manually

1. Open OWA.
2. From the left menu, right-click the name of the inbox and select Create new folder.
3. Name the folder accordingly. For example: To be deleted.
4. From the header, click the cog icon and select Options.
5. Select Mail > Automatic processing > Inbox and sweep rules.
6. Click the + icon to create a new rule.
7. Fill out the corresponding fields:
   • Name: The name of the rule.
   • When the message arrives: The conditions so that only the needed emails are selected. In this case, you would select: It was sent or received > Received from > email@address.com>.
   • Do all of the following: The actions that will be taken. In this case, you would select Move, copy, or delete > Move the message to folder > To be deleted.
8. Clear the check box for Stop processing more rules.
9. Click OK.
10. Confirm that when an email from Jira arrives, it is automatically moved to the To be deleted folder.
11. Select all messages in the To be deleted folder, hold Shift, and press Delete to permanently delete all emails in that folder.
12. Create a repeating task to remind yourself to do this at frequent intervals.

Automatically empty Deleted Items

1. Open OWA.
2. From the head, click the cog icon and select Options.
3. Select Mail > Automatic processing > Message options.
4. Select the check box for the option Empty the Deleted Items folder when I sign out.
5. Click Save.