Why are emails bouncing back in AgentOS?
Emails can bounce back for a number of reasons, most commonly because the recipient's inbox is full or their email address has been identified as invalid. Any bounce back will include an attachment explaining the cause.
When an email sent from agentOS bounces back, it will arrive with an attached text file that explains the reason for the failure. This is the first place to check when investigating a bounce.
Most common cause
The most frequent reason for a bounce back is a problem with the recipient's email account at the point of sending — either their inbox was full, or the server identified the email address as invalid.
If agentOS detects that an email has failed a number of times, it will automatically remove the email address from that person's profile as a safety measure. This prevents the system from repeatedly attempting to send to an invalid address, which could cause a backlog of failed emails. When this happens, the removal is logged under Person Details > Notes Tab > Confidential Notes on the relevant contact record.
⚠️ Important: If you notice an email address has been removed from a contact's profile, check the confidential notes on their record for context before re-adding it. If the address is genuinely invalid, update it with the correct one before attempting to resend.
If you are unsure of the error message
If you have checked the attached text file but are still unsure what the bounce back error means, contact support at support@agentos.com with the example email including the date and time it was sent. The support team will investigate and provide further clarification on the cause.