Horde Webmail Application - What's going on with this specified error?

[mcmmsagh]

Okay, everyone, I seriously need answers. The case is this: during the course of last night AND this morning, I was trying to send an email to a certain address under the Horde Webmail platform (the names and site email addresses are undisclosed in this post; however, the address IS a legitimate one) to ask about certain things in regards to what I am doing and directing them to my site that is hosted here on X10Hosting.

Here's the problem: when I tried to see about actually sending the email inquiry to them, I run into this error:

There was an error sending your message: Message could not be delivered - the address was not found, unknown, or is not accepting messages.

Can anyone help me clarify what in the world is going on here? Because I don't think that I was doing anything wrong when I was composing the said email inquiry in question (and one again, the email address that I was trying to send it to IS legit; they even listed it on THEIR website in terms of the email address they use to receive correspondence).

Many thanks in advance to anyone here who can help me get to the bottom of this matter. Take care for now.

 

[essellar]

The address you are trying to send to is rejecting the mail, probably because of where it's originating from (either the main domain or an IP range). The only thing strange about it is that it isn't doing it silently - ordinarily, spam filters won't tell the sender anything that could be useful. That likely means they are using a very old mail system and outdated spamhaus-type lists. If you want to communicate with them, you'll need to send from a address they will accept mail from; clicking the Send button harder won't help, nor will anything that can be done at this end.

 

[mcmmsagh]

In terms of the IP/domain, are you referring to the ISP connection that I am currently using? Because that is now my assumption at this point.

 

[essellar]

No, the email address (the part after the "@") that you are sending from, or rather the last two parts of it. So if you're sending from somename@subdomain.example.com and they have example.com listed as a known spam source, they will reject your mail. The other alternative I mentioned is that they have blacklisted the IP address of the server you're sending from, or have blacklisted all of x10Hosting's IP addresses. It has nothing to do with where you're connecting from or which email application you're using; it's all about the sending address.