MessagingEngine.com has a number of different locks to avoid abuse of our systems. These include:
If you send a message to someone who has had their account locked, or from an external address, IP or other blocking characteristic, you will receive a delivery notification error like this:
I'm sorry to have to inform you that the message returned below could not be delivered to one or more destinations. For further assistance, please send mail to firstname.lastname@example.org If you do so, please include this problem report. You can delete your own text from the message returned below. The Postfix program email@example.com: host messagingengine.com said: 554 firstname.lastname@example.org; Recipient address rejected: Account locked for abuse or overuse; see http://mail.messagingengine.com/docs/locked.html
You can work out what caused the block by looking at the response message
This means that this account has been locked. There are two reasons why an account is locked: either the user breached their Terms of Service (such as by spamming), or they have gone over their bandwidth quota. If you received an unsolicited commercial email ('spam') which contained a reference to a messagingengine.com address, that address would have been terminated because the messagingengine.com Terms of Service do not permit this type of use. If you want more details of why this email was rejected, please contact the Postmaster.
The sending address email@example.com has blocked due to excessive use, abuse or some other reason. If you want more details of why this email was rejected, please contact the Postmaster.
The sending host was listed in a database of known open relays, compromised hosts, or spam sending hosts (RBL). MessagingEngine.com only uses a smaller number of known high quality RBLs to block hosts. Please see the accompanying link to see why your sending server was listed. If you want more details of why this email was rejected, please contact the Postmaster.
A number of spamming systems use a common signature in the 'HELO' greeting command used when sending emails. We block hosts trying to send email with these greetings. Unfortunately a small number of home email clients also use these greeting signatures.
A work around for this is to change your client to send email via port 26, instead of the normal port 25. In Outlook Express, you can do this by going to Tools -> Accounts -> (select account) -> Properties -> Advanced tab. Then change your Outgoing port (SMTP) from 25 to 26.
Most email clients make it relatively easy to change the SMTP port and you should consult your email clients documentation. For Eudora, it's a little tricky. See this link for more information.