mac.com addresses/Proof Point blocking Zoho AGAIN

mac.com addresses/Proof Point blocking Zoho AGAIN

Zoho.com appears to be on mac.com's blacklist (via Proof Point) again - can you please get it whitelisted?  This has happened before - I have no problem sending emails, EXCEPT to multiple mac email addresses.  I've clicked the link provided below, and it says it's not being blocked, but I continue to not be able to send mail to those addresses, so it clearly is being blacklisted.  I send very little email, so this is not a bulk issue.

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A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. 

xxxxxx@mac.com  Invalid Address, ERROR_CODE :550, ERROR_CODE :5.7.0 Blocked - see  https://support.proofpoint.com/dnsbl-lookup.cgi?ip=74.201.84.156:   xxxx@mac.com