[Skunkworks] SMTP Unable to receive mail

Hello skunks, My SMTP server hosted at safaricom has not been receiving mail for the past 4 weeks. Doing an email trace, I get:"Please turn on SMTP Authentication in your mail client. smtp02.safaricombusiness.co.ke [41.203.208.120]:32221 is not permitted to relay through this server without authentication." Am neither receiving on webmail or client. Any pointers to this? Safaricom seems at a loss of what to do to solve this issue.