When sending email replies from the Inbox, there are times when emails fail to be delivered because of a problem with the recipient’s email account or provider. In these circumstances, we’ll surface the error message that their email provider sent back to us when we tried to deliver the email.
When the customer’s email provider sends back the error, we add a note to the conversation to surface the error message, along with the email address that couldn't receive your reply.
These are errors that Intercom has no control over. They represent a problem with the recipient’s email account or email provider, rather than a problem with Intercom. For example, if the recipient’s mailbox is full, or they have changed their email address.
When receiving errors like this, you can either try sending again later, or reach out to the customer through another address or channel if available.
Common delivery errors
These are some error codes that are commonly received when an attempt to deliver an email fails, along with a description of what they usually mean.
Error code | What it means |
550 | This can mean a variety of different things, such as the recipient address not existing, the email being filtered as spam, or the mailbox being full. The error message usually provides more detailed information about what’s going wrong. |
550-5.1.1 | This typically means that the email address you are trying to send to is not valid. The recipient may have closed their email account, or there may be a typo in their email address. |
550-5.7.1 | This error is often associated with issues related to email security, spam, or policy violations. The email may have triggered spam or virus protection filters, failed authentication checks, or been rejected due to policy violations related to the source or content. |
552-5.2.2 | This indicates that the recipient's mailbox is full and cannot accept any more messages until space is freed up. |
554-5.4.4 | This typically means that the recipient's mail server could not find a route to deliver your email. DNS may be misconfigured on their mail server, there may be policy restrictions that block certain types of email, or there may be a temporary issue with the server or network. |
554-5.4.7 | This typically means that the recipient's mail server could not find a route to deliver your email. DNS may be misconfigured on their mail server, there may be policy restrictions that block certain types of email, or there may be a temporary issue with the server or network. |
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