Issues and errors

  • SMTP error codes: what they mean

    When an SMTP send fails, an error code is returned by the server to indicate the nature of the problem. This article explains what the most common error codes mean and how to respond in each case.

  • What file types can I send as an attachment?

    The Cyberimpact SMTP Relay accepts attachments in most common formats. This article presents the allowed file types and the rules to follow for your attachments to be processed correctly.

  • Why was my email rejected?

    When an email is refused by the SMTP service, it means the message was not accepted by the server and was not forwarded for delivery. This article presents the most common causes and the actions to take to resolve the issue.

  • Why is an email in "Deferred" status?

    The Deferred status indicates that a delivery attempt for the email failed temporarily. The message has not been permanently refused — the system can make new attempts. This article explains what this status means and what you can do.

  • What is the difference between a soft bounce and a hard bounce?

    When an email cannot be delivered after several attempts, a bounce is generated. There are two types: soft bounce and hard bounce. This article explains the difference between the two and what you can do in each case.