Zoho added to SORBS blacklist?

Hello,

I've had emails to one of my suppliers bouncing all day so got in contact with their IT department. Their reply below;

"It seems that the email providers you use (zohomail from what I can see) have recently been added to a blacklist which means any messages you send to us get bounced.

I have attached the logs from our mail server so you can provide them to your IT support.

Additionally the link below takes you to MX toolbox (a resource for interrogating blacklists) and indicates that your email provider is listed on the SORBS blacklist.

http://mxtoolbox.com/SuperTool.aspx?action=blacklist%3a74.201.84.155&run=toolpage"

Having to make phone calls back and forth all day has really affected my business. I would appreciate it if someone could get back to me to resolve this.

Regards,

Chuck