Failed Emails and Deferred Emails

Your administrator can set an email address to receive notifications of failed emails sent from BDP in Configuration. The information contained in the failed emails can be limited. This is generally to prevent bad actors improving their understanding of how to bypass security measures. Sometimes the emails may be deferred for a period of time or may be “bounced”. See below for more information.

Bounced Emails

When emails sent from BDP fail, they are categorised as “bounces”. These can be divided into:

  1. “Hard” (Permanent issues); and
  2. “Soft” (Temporary issues)

Hard Bounces
Indicate a permanent reason for email non-deliverability, such as a non-existent email address or a permanently full mailbox.

Soft Bounces
Suggest temporary delivery issues, like a full mailbox or a temporary server problem. BDP will attempt to send future emails to an email address that has experienced a soft bounce, but if they continue to bounce, they then may be treated as hard bounces.

Soft bounces aren’t resent for the following reasons:

  • Protects sender reputation: Repeatedly trying soft-bounced emails could make BDP look like a spam sender.
  • Mail servers often handle retries: Some recipient servers will retry delivery if the issue is temporary.
  • Invalid Email Addresses: Typos, outdated addresses, or simply addresses that no longer exist.
  • Server Issues: Temporary problems with the recipient’s email server.
  • Spam Filters: Emails might be flagged as spam and blocked by the recipient’s email provider.
  • Email Firewalls: Corporate or ISP firewalls might block emails from BDP’s email provider, Mailchimp.
  • DMARC Policies: Changes in DMARC policies can affect email delivery, especially if using Gmail or Yahoo as your “From” address.
  • Mailchimp Isn’t Allowlisted: If BDP’s email provider (Mailchimp) IP addresses aren’t on the recipient’s email server’s allowlist, emails might be blocked.

Deferred Emails

A deferred email status indicates that the receiving email server is temporarily unable to accept the message, often due to a busy system or technical issues.

Why Emails Might be Deferred

  • Server Overload: The receiving server might be temporarily overloaded or experiencing technical difficulties.
  • Spam Concerns: The inbox provider might see too many spam complaints for emails from your sender.
  • Rate Limiting: The receiving server might be temporarily limiting the number of emails it accepts from a specific sender.
  • Full Inboxes: Similar to soft bounces, deferred emails can also arise from full inboxes.

BDP’s email provider will continue to attempt to deliver the email for upto 72 hours. During this period:

  • It makes multiple retry attempts at varying intervals.
  • The exact retry schedule depends on the recipient server’s response.
  • If the email is still undeliverable after 72 hours, BDP’s email provider marks it as a soft bounce.

In some cases (typos as an example) it is easy to identify the cause and fix the problem. Otherwise it is best to monitor for any patterns.

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