The AntiSpam service of DominioAbsoluto.Net has some blacklists, public and private, that will reject all mail from listed IPs (they will be listed because spam or malware has been sent from them). The error message will be:
553 Blocked by antispam reputation list: http://nospam.dominioabsoluto.com Listed XXX.XXX.XXX.XXX
The sender will have to contact with his postmaster to do the request to delete the IP from the list (http://nospam.dominioabsoluto.com) and check if it is still sending unsolicited mail (it will cause that the IP will be listed again). The unique responsability to prevent that a client's IP is sending mail is himself or his administrator, so we can't do anything if it has a malware program or virus that is sending spam. The responsability of delete the IP from the blacklist is of the client or of the client's postmaster.
We apply rate limits to connections made by a SMTP client. If you want send us big amounts of email, contact with us on email@example.com or try not to send too many emails in a too short period of time. If you don't do this, your connections will be dropped and you'll see this message:
lost connection with XXX.XXX.XXX.XXX[XXX.XXX.XXX.XXX] while receiving the initial server greeting
We've internal blacklists that will filter messages from domains that do, for example, massive mailings or malware sents. Is not a good policy to reject messages by domain but sometime, we can do it if we receive a lot of mails from an especific domain. The error message will be:
553 sorry, your mail was administratvely denied. (#5.7.1)
If you receive messages like this, contact with your administrator or ISP and he/it will contact with us at firstname.lastname@example.org.
In a near future, SPF checks will be done to every mail. If the check fails, mail will be rejected. Now, this checks are done in the content filter, so if the SPF check fails, possibly, the mail will be tagged as spam or it will be deleted.
Messages with a destination of a domain that is not of our responsability will be rejected, our servers are not open relays.
You will see a message like this if you try to send a message to an external domain through our servers:
553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)
If you receive messages like this, contact with your administrator or ISP to check your mail configuration.
Messages to a inexistant destination will receive next message:
550 That e-mail address does not exist (#5.7.1)
If you receive messages like this, verify the email you are trying to send message really exists, or contact with your administrator or ISP and he/it will contact with us at email@example.com.