Don't send emails to bots

[MarcKaufmann]

We should ensure we send no emails to bots. Either we pass in an extra parameter to the send-email function/do an extra check before every send email. Alternatively, we could change the mail-adapter-send-email-with-template to check in the database whether the email belongs to a bot, in which case it isn't sent. The benefit of the latter approach is that it doesn't require micromanaging every email-send action, so that forgetting to check for bots doesn't lead to email attempts by mistake. @Bogdanp, what do you think?