Question : That old chestnut "550 relay not permitted"

Having searched the forums (fora?) here, this one has raised its head a few times. However, I need to know what the fault is.

I am a member of a n orgainsation that would like to email its members every now and again with personal details that require verification (ie the details are different in every email sent, one to each member, every 6 months)

Using the excellent-looking utility written by Dean Dusenberry (vbSendMail.dll) I have found what I thought I needed to send the emails out. (It's another story as to why this one was chosen but that's not for here).

So I set up my program in VB6, using vbSendMail as a dll and attempt to send the details to the membership database, extracting them from a file and then attempting to send each mail.

As a test, I sent it to myself (the .from field set to "[email protected]") and the .recipient field set to "[email protected]"). Works great.

I then send it using the .recipient as "[email protected]". Works great.

Next test - send it to "[email protected]" and this is where the fund and games starts and where I get the error "550 relay not permitted".

Now the questions: WHo is 'not permitting' the relay? is it my ISP? my PC's own setup? my hotmail account? The .from field has not changed and the .replyto field is set to "[email protected]" as well.

An answer would enable me to try and least resolve how to get round this as my organisation co-members are chomping a the bit to receive the details I need to send out!

Beware! I am not an expert on SMTP, MAPI or other such buzzwords that exist in the emailing community so please try and keep it reasonably simple.

Answer : That old chestnut "550 relay not permitted"

When you send a message from your e-mail client (e.g. Outlook) it goes via SMTP to a mail server, which sends it on to the recipient end. This action (accepting and resending) is a "relay" action. If you send to a user, that "is on the same server", the "relay" is fairly simple - the mail goes into the recipient's maibox. If it's for an external party, the server queues up the message and negotiates a conneciton with the receiving end server. This negotiation can be more or less complex. Sometimes the receiving end checks that the return address is valid and so on. So, if your external mails don't get relayed, you may take a look at what is in the FROM: and REPLY TO: fields in the mails you send.
/RID