I have been using Zoho Mail in conjunction with Outlook and all has been fine for a while but since this last Saturday all new e-mails for all of my Zoho e-mail accounts have stopped appearing in Outlook. They are still received fine in Zoho but not Outlook. I had assumed that the problem was with Outlook but I have tried a couple of other clients (Mailbird and Thunderbird) and the same happens, no new e-mails after last Saturday.

Any help, suggestions, solutions much appreciated.