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Could not send: error= -1 Status: 550 5.7.1 Unable to relay for (email address)

Keywords: Could not send:  error= -1 Status: 550 5.7.1 Unable to relay for 


Anyone have any ideas what's causing this?
Could not send:  error= -1
Status: 550 5.7.1 Unable to relay for (email address)
We're converting from a local Exchange server hosting our e-mail to something based on ADS. I don't entirely understand the new system (not much up on ADS).


  1. Go check the mail for...
    and see if there are any good bounce messages in there.

  2. Also check with your mail admins.

Basically it seems that the mail server you are connecting to does not want to send the email to the "to" address.

This is usually because you are connection to the mail server from the "outside" of the ip address range that it thinks it "owns".

In any case set up a normal Internet email program (Outlook Express, Eudora, Netscape Mail, The Bat, etc) and see if you can make it work from the same machine and the same mail host.

Question (cont'd):

OK, it's time to revisit this fun little issue.

The big bang happened last night, and I'm still getting the same error message:

Could not send: error= -1
Status: 550 5.7.1 Unable to relay for
The only changes from my previous posts are:
A) I've upgraded to 2003E,
B) I've added the most recent version of Posite (just ran vcheck)
C) The server info has changed.

I'm still just guessing that they don't have relaying turned on.

For some time now, I've had a WB script running that sends e-mail from my processes via our local Exchange server. Our mail services were just absorbed into the larger University-wide e-mail system, and all I've done in my code is change the host name - now, I can no longer send e-mails.

I already connect with the Exchange server via Outlook for my 'manual' e-mail, it's just the automated ones that don't seem to be working.

As a side note, I saw in my search for 'postie' that you'd created an SMTP server at some time. Have you posted that here? Do you think that I might be able to run my own server to send the mail, or do I need to have significant administrative rights (in particular, to a domain) to get that up and running? I'll just by=pass the corporate network if that's what it takes...


If you want to prove that it is not WinBatch that is having the problem either use POP3/SMTP e-mail client (Outlook Express, Eudora etc).

Or do the following:

The following is you pretending to be an e-mail client.

Run 'Telnet 25' (replace with your server name, the 25 tells it to conect on port 25 (the SMTP port))
(} means something the server sends you, < is something you have to send the server (don't use the {))

The telnet screen should come up and the mail server should return something like:

}220 ESMTP .......
You need to type in
You will most likely not see what you type unless you have turned on local echo.

It should come back with something like

}250 Hello
Next you need to tell it who the mail is coming from
You should get back something like
}250 Sender ok
Then tell it who to send the e-mail to This is the point you are likly to get the error. If you do then they are not letting you send messages via SMTP.

If you get something like '250 .... Recipient ok' then it is going to let you send the mail and you can exit by typeing QUIT.

For more info have a look at RFC 821 (google search).

NOTE: The SMTP server that is in the Tech Database is only for receiveing, but I have the code and a Extender that do allow you to send e-mail directly to the end e-mail server. But I've never used the Extender in live code for any length of time. As long as you are not firewalled to much you should be able to run that code if you want it.

Outlook is not the same as Outlook Express when you are conencting to Exchange. Outlook uses a Microsoft special protocol to talk to the Exchange server, while Outlook Express uses POP3 and SMTP. When you are using the postie extender you are using SMTP to send e-mail so if you are wanting to test some other application you need to use Outlook Express, Eudora or Netscape etc.

Question (cont'd):

>Then tell it who to send the
>e-mail to
>This is the point you are
>likely to get the error. If you
>do then they are not letting
>you send messages via SMTP.
This was _exactly_ the point of failure. The sad thing, is that I'm using an INTERNAL e-mail address. I'm not trying to leave the domain with anything.
>For more info have a look at
>RFC 821 (google search).
Thanks for all your help, Iain! WB is like a rubber band - once you stretch it, it's never quite the same as it used to be. You're one of the better stretchers out there!



When I sent a copy of your instructions to the E-mail support people (along with the failures they produced), they decided to give me the name of the server that's set up to do relaying.

Works much better now.

Thanks again Iain. Having a bigger hammer always helps in getting things moving!


Glad that you managed to get it sorted. It looks like they have most of the Exchange servers only allowed to talk to the other e-mail servers.

If there was no server that was set to allow relaying the next option was to use the MAPI Extender so that you would be talking to Exchange as if you were Outlook.

Article ID:   W15413
File Created: 2017:07:28:13:58:34
Last Updated: 2003:05:13:11:27:33