Zoho mail problems again. Cannot send mail, incoming mail missing or late.

Zoho mail problems again. Cannot send mail, incoming mail missing or late.

I noticed these problems starting this morning Jul 4 Pacific time.  The sending problem has occured at least twice in the past, with the following error: "Unable to connect SMTP server:whatever.com Reason:Authentication failed:535 5.7.8 Error: authentication failed: authentication failure".   And it was determined to be a problem with Zoho in those past instances.  

Sorry Zoho...I've tried to be patient with Zoho problems, and I'm the Zoho advocate at my workplace, but my credibility and Zoho's credibility is getting shot.  

What's going on?  Please help right away.  Thanks.