Unable to connect SMTP server:smtpout.mail.zoho.com Reason:Authentication failed:554 5.1.8 Sender Address Blocked

Unable to connect SMTP server:smtpout.mail.zoho.com Reason:Authentication failed:554 5.1.8 Sender Address Blocked

I sent several emails quickly to my boss Ben Balson at Remote Recycle, and could not continue sending because the server thought I was spamming him.  I am not.  Please reinstate my sending privileges and let me know how I can avoid this in the future.

Thanks,

Fred Meltzer
fred@remoterecycle.org