So I had a custom domain email from Zoho and I was able to send emails from this account through my gmail. 2 days ago I added another user. This user is not able to receive any emails, that's the first issue, moreover, even though I haven't changed anything else other than adding this user, now I am unable to send email through my gmail account with the first user either!

I have opened a case with priority "I am stuck, need assistance", haven't got a single reply in about 36 hours. I am unable to reply to my clients. Thank you Zoho!