I just sent out an urgent newsletter email to my clients and received a notification indicating that 12 emails were delayed (all of them were *@hotmail.com and *@live.com addresses). My husband had this happen last night as well when trying to send an email to a *@hotmail.com address.

According to Microsoft's website [ http://mail.live.com/mail/troubleshooting.aspx#errors], it seems that Zoho's mail server's IP has been throttled.

ResponseCode 421, RP-001

"The mail server IP connecting to Outlook.com server has exceeded the rate limit allowed. Reason for rate limitation is related to IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help."

PLEASE HELP!

See below for a shortened version of the original error email:

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 Jan 2017 04:56:13 -0800

from *******@********.***

----- The following addresses had fatal errors -----

[Status: Error, Address: <*******@*******.****>, ResponseCode 421, RP-001 (COL004-MC6F22) Unfortunately, some messages from 135.84.80.217 weren't sent. Please try again. We have limits for how many messages can be sent per hour and per day. You can also refer to http://mail.live.com/mail/troubleshooting.aspx#errors.]

Message will be retried for 4 more day(s)