The office experiences problems with their mail-clients. The employees inboxes are rebuilding or keep syncing. Because I don't work there I can't really seem to find the problem. Internet (browsing) works fine and there are no incorrect settings to be found on the settings panel for each of the users.

I've seen Zoho encountered DDOS attacks recently, and I wondered if this might be the problem. Otherwise there may be private network problems within the offfice. 

My question is, could you check whether this problems occur because of Zoho. The domain name is bigbrands.nl. Depending on the result different solutions will take effect.

Thank you for your time. Hope to hear from you soon.

With kind regards,
Tim Gruijters