451-4.4.0 554-No SMTP service 451-4.4.0 554-Bad DNS PTR resource record. 451 4

Hi all, we have Exchange 2010 running on Server 2008r2 and have some email stuck in the outgoing quee with the following code in the log :-
"451-4.4.0 Primary target IP address responded with: ""554-kundenserver.de (mxeue101) Nemesis ESMTP Service not available
451-4.4.0 554-No SMTP service
451-4.4.0 554-Bad DNS PTR resource record.
451 4.4.0 554 For explanation visit http://postmaster.1and1.com/en/error-messages?ip=176.35.114.125&c=rdns."" Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts."


Any ideas?
many thanks
ShifnalAsked:
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Seth SimmonsSr. Systems AdministratorCommented:
Bad DNS PTR resource record.

check your public PTR record to make sure it matches your sending server public IP address

check if your domain and/or IP address are blacklisted anywhere

https://mxtoolbox.com/blacklists.aspx

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ShifnalAuthor Commented:
thanks for theis
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