You might well have already seen this video in the docs page Competencies but I will post it anyway just in case:
Mary Cooch (personal account)
Αναρτήσεις που έγιναν από τον/την Mary Cooch (personal account)
Are they using a different authentication from the normal one? For example with OAuth2 via eg Google, they cannot change their password - they can only do it via Google (etc) You could change the message in the return email to make this clearer.
Hello José. I am moving your post to the Languages forum as this is about translating. You will get a response there soon 
Just to inform you both I have split this discussion from the earlier discussion on Scalablity, so no need to start a new thread, and thanks for pointing it out Visvanath.