mail not accepted by other mailservers? 1

[leploep]

Hello,

I'm in a total loss here. Its way too hot to think a bit logically so i'm trying the extensive knowledge you guys posess.

We have a website that generates mail and sends it through our exchange server wich in turn will try to deliver it to the end-user. However the receiving mailserver is rejecting it without a reason given, the mail stays in the que (being resend every 30 mins or so) until the time-out after 2 days. And a nice NDR with 4.4.7 is generated.

When i hit "send again" and send it from my outlook client using the same "sender an recipient address" it goes out nicely.

So this would rule out any misconfigure on the exchange server i would think.(blacklists,dns-checks,etc) Or am i not thinking straight?

But what could it be then???

I hope someone can shed some light on this dark situation

 

[ReddLefty]

More and more Email servers do "reverse look-ups" when they receive email to insure that it's a valid email server. This reduces spam. Make sure your IIS SMTP is using your Exchange server and not it's own SMTP. This would explain why you can send threw your Outlook, but it fails when going threw your SMTP in IIS cause the server your web page on might not have an MX record, so the reverse lookups would fail.



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