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Exchange 2010 sending e-mail - 450 4.7.1 Client host rejected: cannot find your hostname
Hi,
We recently replaced our internet connection.
When we send e-mail to specific external domains we get this error:
 450 4.7.1 Client host rejected: cannot find your hostname, [MyExternalIP]
according to google I need to set the PTR record so that a reverse dns for [MyExternalIP] would return "mail.[mydomain]". So I contacted my provider yesterday and they now have set it. I can even test it with online tools and it now returns "mail.[mydomain]".
It has been almost 24 hours now since the change and I still see this error in exchange queue viewer for atleast 2 external domains.
some facts:
- other domains do accept our mails.
- my SPF record is correct and google says SPF pass.
- My exchange server uses "mail.[mydomain]" to say HELO or EHLO.
- I do have some internal DNS issues but that couldn't be the case because the receiving mail server (a different company) will never use my DNS.
- the mails dont bounce immediately, my exchange will keep trying and I can tell the queue to retry. I did this several times.
- I also restarted Exchange and emptied the queue and tried mailing again.
should I just wait longer or is there something else I can do or check?
kind regard,
Ramon.
We recently replaced our internet connection.
When we send e-mail to specific external domains we get this error:
 450 4.7.1 Client host rejected: cannot find your hostname, [MyExternalIP]
according to google I need to set the PTR record so that a reverse dns for [MyExternalIP] would return "mail.[mydomain]". So I contacted my provider yesterday and they now have set it. I can even test it with online tools and it now returns "mail.[mydomain]".
It has been almost 24 hours now since the change and I still see this error in exchange queue viewer for atleast 2 external domains.
some facts:
- other domains do accept our mails.
- my SPF record is correct and google says SPF pass.
- My exchange server uses "mail.[mydomain]" to say HELO or EHLO.
- I do have some internal DNS issues but that couldn't be the case because the receiving mail server (a different company) will never use my DNS.
- the mails dont bounce immediately, my exchange will keep trying and I can tell the queue to retry. I did this several times.
- I also restarted Exchange and emptied the queue and tried mailing again.
should I just wait longer or is there something else I can do or check?
kind regard,
Ramon.
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