IN NO 451 451

This error message occurs when the Immediate Message Processing cannot successfully receive a message before its internal timeout triggers it to abort. If several of these occur in quick succession it could mean that the server was performing slowly at the time and a service log review should confirm. If the mail log is full of these error codes and no mail is coming in, it would suggest there is a definite performance problem that needs to be addressed or the timeout needs to be increased. When Emailtopia’s Response server returns this error message to the originating server, it should cause the server to retry sending the message later. This error should not lead to permanent message deliver errors unless it isn’t resolved before the originating server exceeds it’s maximum number of hours to attempt delivery. This time limit is approximately 3 days.

OUT ERR 451 Connection reset

This temporary error message indicates that the outgoing SMTP connection was interrupted and reset, no message was delivered and no specific error code was returned from the destination SMTP server. This can occur either due to network connectivity issues, or could occur as the result of intermediary software killing the SMTP connection for one reason or another, i.e. flagging content as spam.

POP ERR 901 Connection failed: Connection to server failed

This is usually a temporary error message that indicates that the most recent connection to the POP server has failed. This message should be different from the error that appears if the credentials for the POP account are incorrect, but running a test from the mailbox under the POP pickup settings will confirm if it’s a connectivity issue or an authentication issue.

OUT ERR 550 #5.1.0 Address rejected

This error message indicates that the destination server for Emailtopia’s Response’s messages has rejected one or more messages based upon the destination or source address. This can happen when a mailbox is full or when an address is blocked for security reasons.

Permanent Error Notifications

IN ERR 552 User does not exist

The most common occurrence of this message is when someone attempts to send a message directly to an Emailtopia Response user from an external source, which is not supported by the Emaitopia Response server. The message will bounce back to the source indicating that the user does not exist. The most common time we see these messages is when a user’s Outlook has sent out a read receipt response to a customer, or the agent has requested a read receipt and the response is coming back for the user’s address as opposed to the group mailbox address.

IN ERR 552 Mail from


This error message indicates that a message was received which has a From address that matches an entry in the Blocked Senders list in the Emailtopia Response Admin application. For this reason the message was refused by the Emailtopia Response server without being received. Although this can normally be safely ignored, if there are any indications that the postmaster@ address has been added to the blocked senders list it will need to be removed or it will interfere with the operation of alerts.

IN ERR 552 Relaying from host not allowed as host not in allowable relay list

This error message indicates that someone tried to send out a message through the Emailtopia Response server that was not a reply destined for the Emailtopia Response server, and the user’s host name or IP range is not in the RM server’s acceptable relay list under Emailtopia Response Admin -> Server Settings -> SMTP Server.

OUT ERR 530 5.7.1 Client was not authenticated

This error message indicates that the Emailtopia Response Server’s upstream server (as specified under RM Admin -> Server Settings -> SMTP Server -> Forward Outgoing Mail To) requires authentication to successfully allow incoming SMTP connections and the RM Server has not been configured with authentication parameters, or the authentication parameters are incorrect.

OUT ERR 550 5.7.1 Client does not have permissions to send as this sender

This error message indicates that the “Client” (Emailtopia Response in this instance) does not have permission to send an e-mail using the From address attached to the message. This most commonly occurs when a customer is required to use authentication for their outgoing mail flow and they have to grant the account they’re using to login to the outbound mail server permission to send as the other e-mail addresses.