That’s the least to do, yes. Another option would be to use a long random string as email, like discourse does it to reply to post comments. Maybe a combination of both.
this would be a great feature.
One approach on this is offcourse to send a task via email.
Another approach is having Vikunja check a specific folder ini the user-set mailbox.
For instance: every 5 (or 10 or whatever) minutes, Vikunja checks te folder “todo” in my gmail, imports all unflagged mails in that folder and flag them.
Or another example: Vikunja checks the inbox in my gmaiil for flagged mails, imports them and moves them to e specified folder.
Both examples are inspired by the way Paperless and Paperless-NG works.