What would be the correct way to set a 'Sender Matches Pattern Condition' rule (i.e. email address)?

The UI implies on the format as follows: Full or Partial Email Address (e.g., example.com, [email protected], sample.example.com, jsmith, jsmith@example)

Note that using a format such as @example.com will fail, and as a result the rule will not be met. Instead, use the format example.com

If you are creating a exception for file upload (URL as a recipient and email domain in sender pattern) it should be added in format *example.com or if you want to make sure that this only applies to that specific domain and not a possible subdomain, you use *@example.com

Note : If protocol is anything other than SMTP, format for whitelisting domain to be used should be *@example.com