Email Bounce Reasons/Types
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      2. Email Bounce Reasons/Types

      What are the email bounce Reasons/Types?

      Explore the diverse range of factors that lead to email bounces, from temporary issues like soft bounces to more severe problems like hard bounces.

      A bounce message (reason) is also called a Non-Delivery Report/Receipt (NDR). It's an automated message from the recipient's email server with details about the specific problem with the email delivery.

      Common Email Bounce Reasons/Types

      There can be many technical reasons an email can bounce. Here are the most common email bounce reasons.

      • Hard bounce: usually indicates a permanent error, but can also be caused by a strict email security filter. To protect your email sender reputation, HubSpot excludes these contacts from future emails.
        • Unknown user: this indicates a permanent error caused by an invalid email address. HubSpot automatically drops contacts from future emails if they bounce for this reason. If a contact bounces for this reason across three HubSpot accounts, the email address is globally bounced.
        • Mailbox full: this indicates a permanent error caused by an abandoned email inbox. HubSpot automatically drops contacts from future emails if they bounce for this reason. If a contact bounces for this reason across three HubSpot accounts, the email address is globally bounced.
        • Content: something in the email body or subject triggered spam filters. To solve the problem, ask the contact to add your sending IP addresses to their allowlist, then unbounce the contact in HubSpot.
        • Spam: something in the body, subject, or From address of the email that is classified as spam by the recipient's email server. To solve the problem, ask the contact to add your sending IP addresses to their allowlist, then unbounce the contact in HubSpot.
        • Policy: the email did not pass one of the security policies of the recipient's server, but it is not explicit about which one. This includes DMARC; DKIM, and SPF authentication failures. To solve the problem, ask the contact to add your sending IP addresses to their allowlist, then unbounce the contact in HubSpot.
        • Other: the response from the recipient's email server wasn't specific enough to categorise the bounce. To solve the problem, ask the contact to add your sending IP addresses to their allowlist, then unbounce the contact in HubSpot.
      • Soft bounce: indicates a temporary problem with the recipients server, or another temporary technical problem. Contacts who soft bounce are eligible to receive future emails from you.
        • Temporary technical issue with the recipient's email: the recipient's server may be overloaded, timing out, or undergoing some configuration changes that prevented it from accepting the message. Create a clone of the original email and send it to the affected contacts at a later date. For a one-to-one sales email, try sending your message again at a later date.
        • Rejected by recipient's email security filter: there's a temporary problem with the recipient's server or HubSpot's sending IP addresses. To solve the problem, ask the contact to add your sending IP addresses to their allowlist. Then create a clone of the original email and send it to the affected contacts at a later date. For a one-to-one sales email, try sending your message again at a later date.
        • Your IT team has not authorised HubSpot to send emails on your behalf: your IT team set up a custom DMARC policy that needs to be updated to include HubSpot. Reach out to your IT team to send them documentation about using a DMARC policy with HubSpot.
        • Temporary technical issue: there may have been a temporary technical problem with the recipient's email server or HubSpot's email server. Create a clone of the original email and send it to the affected contacts at a later date. For a one-to-one sales email, try sending your message again at a later date.
      • Pending bounce: caused by a temporary technical issue with either the sending or receiving email server. HubSpot continues to try sending the email for up to 72 hours. If the message isn't delivered during that time, it becomes a soft bounce.
      • Global bounce: a hard bounce for a permanent reason across three or more HubSpot accounts. Permanent bounces include unknown user and mailbox full. Global bounces are dropped from future emails across all HubSpot accounts