I'm having problems with a PLC (programmable logic controller) that has an email platform that uses cipher TLS_RSA_WITH_RC4_128_SHA (0x0005). 

Everything had been working flawlessly with the SMTP settings: smtp.zoho.com, port 465, authentication required - yes.

Earlier this year it stopped, and from what I can tell it is getting hung up on negotiating a connection. Has ZOHO had a major change in secuirty settings where this cipher is no longer supported?

Any ideas?