Hi Patrick,

It's not clear from your mail who is blocking who - but I am assuming
user@recipientdomain.com is the target.

Most likely - this user/IP is blocked by Trend Micro's blocking list.

Check: https://ers.trendmicro.com/

Cheers,
Tony


On 26/10/2016, Patrick Mathenge via skunkworks
<skunkworks@lists.my.co.ke> wrote:
> Hi Skunks,
> I have an email account that keeps getting below email while sending to a
> certain domain. Other accounts are able to send to same exact domain
> without issues.Here is the log
>
> --> RCPT To:<user@recipientdomain.com
> <Dominiek.vangansbeke@biobestgroup.com>>
>
>   <-- 550 5.7.1 <user@recipeintdomain.com
> <Dominiek.vangansbeke@biobestgroup.com>>: Recipient address rejected:
> ERS-RBL.
>
>   --> RCPT To:<user@recipentdomain.com <Thierry.lefebvre@biobestgroup.com>>
>
>   <-- 550 5.7.1 <user@recipientdomain.com
> <Thierry.lefebvre@biobestgroup.com>>: Recipient address rejected: ERS-RBL.
>
>   --> QUIT
> Kind Regards,
> Patrick Mathenge
> Cell: +254722630969
> Linkedin Profile <https://ke.linkedin.com/in/patrick-mathenge-132b3b19>
>


--
Tony White