I am behalf this on behalf of @Raimund-Liebert-WMAT.
He created his Phabricator account via MediaWiki.org OAuth login. After logging-in, the system asks him to confirm his e-mail address. He tried so repeatedly, but the confirmation e-mail never arrives. We double-checked the e-mail address and it is correct. We did check spam folder. One of his colleagues (@Annemarie.Buchmann) used the same e-mail provider, which potentially rules out the e-mail server refusing it.
We are a bit at loss. Would it be possible to check on Phabricator side whether the problem might be there?
Interestingly, there is close to nothing you can do without a verified e-mail address − including changing it in your settings (as noted in T124351 and others), but also having the search bar to look through Phabricator for similar tasks ;-)