Email forwarding is occasionally failing

Email forwarding is occasionally failing

I have received the following message from zoho a few times in the past few days. The email address that zoho claims cannot be forwarded to is actually the same email address that is being forwarded the failure message, but from a different zoho account. The account that is having the problems is fit@fitnessincenitve.com, which has two forwarding addresses, one of them being kenbrown@optonline.net. The other email that also forwards to that address is ken@fitnessincentive, through which I got the notice that the forwarding failed. As I stated, this is happening sprodically - I have tested and received forwarded messages from this zoho account successfully. But I have also seen repeated failures. Please advise. 

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Dear ken@fitnessincentive.com ,

Problem while forwarding mails to kenbrown@optonline.net . Repeated failure will disable email-forwarding.

Regards,
Zoho Mail Mail Administration

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