For the last couple of days, all users on my account are failing to connect to the Zoho EU mails servers. This is using mobile app on various phones & desktop mail clients on different computers. Everything works fine when using webmail & email is still landing in the inbox & can be sent.

Zoho support has said there's a dedicated EU support portal which I can't find mention of anywhere, so they've just closed my support ticket. 

Please help!