Greetings,
I did a search on this forum before I made my post. The funny thing is that if you try do a search now on '550 administrative error' or '550 Administrative prohibition' with the Search on All Items option selected, the only topic that's ever returned is this one that I made.
Different results might appear depending on whether you are logged in or not. I get 11 matches for "550 administrative prohibition".
If I remember correctly, you said on those posts that the reason for 550 administrative prohibition errors is that the administrator of the servers where these errors occur intentionally set some sort of ban for sending out email going to certain domains. And you also said that the problem is not caused by listmailpro but is caused because of these policies.
Yes, however I also offered 3 important possibilities:
1. Limitation on messages per hour or day - please ask your host about the possibility of such limitations.
2. Rare limitation in that all "Bounce to email" and "Send from email" addresses must exist in your control panel as either a mailbox or an email forwarder.
3. AUTH requirement - you may need to set the SMTP AUTH feature including the host, username and password of a valid mailbox on the server.
But I don't think any hosting admin would intentionally place a prohibition on being able to send out emails to email addresses that are on the same domain, that would be ridiculous.
As in #1 please ask the host if there are any hourly or daily limits on email. As in #2, the "From" information can come into play - try adding your "bounce to email" and "send from email" in your control panel.
- Send an Email DOESN'T work, despite the fact that I am just trying to send one message from the listmailpro application to one single email address that happens to be on the same domain.
So it's still my hosting provider that I should check on here you think?
It sounds like your SMTP settings could be off. (SMTP is enabled, correct?) Generally I first try "localhost" as the hostname with no AUTH authorization. If you can't connect to localhost, try "mail.example.com". If you still can't send, enable AUTH with a valid username and password.
Make sure one method of bounce is enabled and the "bounce to email" is on the ListMail domain (and possibly also existing in your control panel). Technically, this sets the "Return-path" header of the email which is invisible to the reader and used for undeliverable returns. With no method of bounce processing selected the "bounce to email" is -not- used and instead the "Administrator Email" is used instead. Therefore with bounce disabled the "Administrator Email" may also need to be on the ListMail domain and possibly need to exist in the control panel.
Please let me know if I can be of further assistance!
Regards