Not receiving SOME email

Not receiving SOME email

I have recently migrated to Zoho, less than a month ago, 6/27/2017 to be precise. Currently I am using the free service. Given my experience to date I am not likely to upgrade as I was planning. I see many replies in the forums from support. As support has yet to reply to any of the emails I have sent them, perhaps I can get a reply here. The first message I sent was the day of the migration.

Ironically my problem is not receiving email from some senders. Not all. Most email gets through. I have verified that I have not received emails from @americanexpress.com, @REI.com, and a smaller client whose domain I do not wish to share. Perhaps Zoho as well. You would know if you have replied to my other messages. All email is downloaded to my desktop every five minutes. It is not stored in my Zoho inbox unless I'm away from my desktop which is never more than a day. Therefore the problem is not exceeding the size of the inbox. I have checked the spam folder at Zoho which is always empty.and the spam folder within Outlook which has been abundantly full since I switched to Zoho. What could be preventing only some of my email from arriving?

The second problem is the amount of spam I have started receiving since switching to Zoho. I average 80 spam messages per day. I'm not sure if my previous host had a better spam filter or if you have sold my address. Why has spam increased so much?

The final issue is notifications I receive from a client. All messages are sent from an address in the form notify@theirdomain.com. These notifications arrive without issue to my desktop Outlook. If I am using Outlook on my phone, they are not accessed. When I look online at my Zoho inbox, they are in a folder called Notifications which is a system folder associated with a tag. Because it is system related, I get an error every time I try to delete either the folder or the tag. How can I see these notification emails from my client on my phone's Outlook app?

Looking forward to finally receiving a response.

Thank you,
Chris