Non Zoho Hosted email accounts?

Non Zoho Hosted email accounts?

I am having sync issues with an email account that isn't hosted by Zoho.  Has anyone else experienced problems in this arena?  It seems that using email hosted by Zoho or other standard email platforms like Gmail, Yahoo, etc are fine, but using my work email (which I can't switch the hosting company) is problematic.  

I recently joined Zoho (mail and CRM) and configured my work email address.  It seems to work fine on my iphone (although it does seem to delay updating the inbox compared to outlook), but using it online (with Google Chrome) through both the Zoho Mail and Zoho CRM applications is having issues.  Every time I open up the mail account for my work email address, it opens with current emails and then starts downloading all of the old emails in my inbox.  I have thousands of emails and this process seems to crash my inbox.  I am hoping this is just a setting that needs to be changed, but I can't get anyone to answer my call when I call support and chat was a waste of my time.  

Prior to starting this thread, I noticed a number of issues with other users email and am now concerned I may be making a bad decision going with Zoho.  

Any thoughts or suggestions will be greatly appreciated!

Thanks,

Tripp Miller