Prevent email verification from going to spam folder

[sync-by-unito]

We surely can improve further on this matter, but that’s also a lot of works
https://sendgrid.com/blog/10-tips-to-keep-email-out-of-the-spam-folder/

Created from Slack: https://dt42-numbers.slack.com/archives/C0323488MEJ/p1644550125340449?thread_ts=1644474176.171669&cid=C0323488MEJ

┆Issue is synchronized with this Asana task by Unito
┆Created By: Ray Hung

[sync-by-unito]

➤ Kenny Hung commented:

doesn't have priority, move this task to product backlog section.