Mail Delivery Status Notification (Delay)

Mail Delivery Status Notification (Delay)

 I have had several messages delayed yesterday, for example
----------------------------
This message was created automatically by mail delivery system.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

The original message was received at Wed, 04 Nov 2015 11:03:47 -0800
 from jruler@zoho.com [jruler@zoho.com] 

    ----- The following addresses had fatal errors -----    
   [Status: Error, Address: <alangleslie@outlook.com>, ResponseCode 421, 4.7.0 Temporarily Deferred]

Message will be retried for 4 more day(s)

    ----- Transcript of session follows -----    

 Received:from [192.168.0.2] (cpc65654-gill16-2-0-cust149.20-1.cable.virginm.net [92.238.224.150]) by mx.zohomail.com
	with SMTPS id 1446660460692462.4861398394479; Wed, 4 Nov 2015 10:07:40 -0800 (PST)
 Message-ID:<563A496A.9030408@zoho.com>
 Date:Wed, 4 Nov 2015 18:07:38 +0000
 From:Jack <jruler@zoho.com>
 User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101
 Thunderbird/38.3.0
 To:Alan Leslie <alangleslie@outlook.com>
 Subject:Re: Pressure Gauge for 8F
 Content-Type:multipart/alternative;
 boundary="------------060200020605000207080606"
--------------------------------------
I was able to resend them via another mail provider.
This is new behaviour from zoho. Is there anything I can do to re-establish normal communications?
(I am receiving emails normally)
Jack Ruler