SMTP Protocol error:

SMTP Protocol error:

Hi , can you help to understand below mentioned error.
12:21:32 SMTP protocol failure: syntax error: 3-digit code not found; -ERR ; too many error commands by mx2.zohomail.com (74.201.154.201) while connected from m6.examplemail.in (x.y.z.a) to mx2.zohomail.com (74.201.154.201)