zoho bouncing emails - 559 Message not committed due to internal error

zoho bouncing emails - 559 Message not committed due to internal error

Have been told that email sent to me have bounced.  Error message they received is:

Delivery to the following recipient failed permanently:

      laura@----.--

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain -----.-- by mx.zohomail.com. [165.254.168.50].

The error that the other server returned was:
559 Message not committed due to internal error

what does the 559 code mean that came from mx.zohomail.com?

Laura