Hi Alice. Yes, you can. Remember that these settings are defined using what is called a "regular expression"--a method of pattern matching frequently used in programming and other applications (Tableau has it too, as a matter of fact!).
Normally, to tell VizAlerts it can send email to any email address in a domain, you'd have:
The special stuff in there just means:
(any character)(<-previous character any number of times)@tableau(treat the next character as a real one->).com
So now you will use the "OR" character, which in regex is a pipe: "|":
Now if either of those two patterns are matched by your recipient addresses, they will pass the test and be sent.
For "default_allowed_from_address", that is applying the pattern only to the "from" addresses specified in your alerts. You could whiltelist "vizalerts@yourdomain\.com|vizalerts@yourotherdomain\.com" if you just wanted to allow the VizAlerts address as the from address. You may or may not want to whitelist an entire domain for that, because it can open the door for folks to spoof emails as if they'd come from someone else more easily, such as an email from the CEO with an embedded image of a viz depicting a Sales bookings decline. Depends on how big your organization is and how much you trust them! Though in reality, if they tried doing anything nefarious it would be fairly simple to see who had done it, so I don't really consider it a serious threat.
Hope that helps!