Our company use Zoho to work. We change provider from our current provider. This provider is from czech republic like us. This provider call Wedos. You are now our new mail webhosting provider. We have domain woodplc.cz and this domain is only in Zoho but we stiil have old domain: amecfw.cz. This domain still work in Wedos provider. We need forward mail from domain amecfw.cz in Wedos provider to woodplc.cz domain in zoho. In Wedos webhosting is set forwarding mail from our old mail adress. From the beginning is everithing work well, but now? Now its some problem on your site. (I think) Can you help me? As example I will introduce mail adress mitev@amecfw.cz. I need mail forward from this adress to mitev@woodplc.cz. Maill now stop forwarding and i have very much mail in my SPAM box. Text of this SPAM mail is: 

-----Original Message----- 
From: Mail Delivery System [mailto:MAILER-DAEMON@wes1-so2-redir.wedos.net] 
Sent: Wednesday, December 13, 2017 2:19 PM 
To: stofferova@amecfw.cz 
Subject: Undelivered Mail Returned to Sender 

This is the mail system at host  wes1-so2-redir.wedos.net . 

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. 

For further assistance, please send mail to postmaster. 

If you do so, please include this problem report. You can delete your own text from the attached returned message. 

The mail system 

<stofferova@woodplc.cz>: host  mx2.zoho.com[204.141.33.55 ] said: 451 4.7.1 
Greylisted, try again after some time (in reply to RCPT TO command) 

Can you help me please? Why Greylisting to our domain amecfw.cz? This problem stand more than one weel. Waiting dont help me. :) Thanks for your suggestion.