Paid for email that could not receive email; zero customer service
I subscribed to Sendmux Pro on 15 Oct 2026 to receive email on my own domain. The domain verified and the dashboard showed inbound delivery active, but both MX servers rejected external mail with "503 5.5.1 You must authenticate first." I tested both directly and got the same answer. Customer service did not exist: I reported it through the dashboard Feedback form (no ticket, no acknowledgement) and by email to their only support address (sent twice, 16 Oct). There is no phone line and no ticketing, and as of 17 Oct nobody has acknowledged any of the three messages. When I tried to close what I had set up, their API refused to delete the mailboxes and the domain (503 and 409 errors). I cancelled and moved to another provider. I want my US$ 7 refunded; I am not interested in credit or a free plan. I will update this review with their response.


