Trouble Exchange Server 5.5 / Sending Spacific E-Mail

[Shoe47]

I have Exchange Server 5.5 running the IMC connector.&nbsp;&nbsp;We host our own email and have a DNS server with the MX record pointing to our Exchange server.&nbsp;&nbsp;&nbsp;Internally I have about 10 to 15 corporate users that cannot send email to specific internet email addresses.&nbsp;&nbsp;Example: User X can send to <A HREF="mailto:jdoe@hotmail.com">jdoe@hotmail.com</A> but cannot send an email to <A HREF="mailto:jdoe@yahoo.com">jdoe@yahoo.com</A>.&nbsp;&nbsp;Message returns as Host Unreachable.&nbsp;&nbsp;What should I be looking for to correct this?<font color=red><b><i><u>Thanks!</u></i></b></font>

 

[click]

If this happens to all of your users, it might be your ISP. Sometimes when you are trying to go from one ISP to another server through the SMPT port(25) it might consider it as a threat(hack) and not allow it access. This error sometimes comes across as &quot;Host Unreachable&quot; when it is actually getting there, but rejecting your &quot;helo&quot; greeting.

 

[lardum]

Have you recently changed IP address on the Exchange Server or has the recipients mail server recently changed address?

 

[Zelandakh]

Are you having problems browsing the Internet too? If so, this suggests it is a DNS issue. Try flushing your DNS cache.