Outlook (office 365 version) suddently can't send / can't contact SMTP servier

Outlook (office 365 version) suddently can't send / can't contact SMTP servier

Several days ago outlook stopped working with Zoho on the send side.  I have tried everything.  The error is that Outlook says it cannot reach or log on to Zoho's smtp server.  This is causing massive problems as I for years have used Outlook every single day with Zoho without issue.