The error is telling you that the domain has no email delivery records in DNS. This doesn't seem to be the case any more though so you should no longer be seeing this error. Perhaps the owner of the domain made some DNS changes recently that took a while to propagate?
>nslookup -type=mx yesrecruit.co.uk 22.214.171.124 Server: cdns01.plus.net Address: 126.96.36.199 Non-authoritative answer: yesrecruit.co.uk MX preference = 10, mail exchanger = mx01.1and1.co.uk yesrecruit.co.uk MX preference = 10, mail exchanger = mx00.1and1.co.uk mx01.1and1.co.uk internet address = 188.8.131.52 mx00.1and1.co.uk internet address = 184.108.40.206 mx01.1and1.co.uk internet address = 220.127.116.11 mx00.1and1.co.uk internet address = 18.104.22.168
Bob Pullen Plusnet Product Team If I've been helpful then please give thanks ⤵