If you are bulk-sending to Gmail you need to be fully aware of their sender guidelines. Be aware that non-compliance with these rules will now result in messages being sent to spam folders, at best, or rejected, at worst. There are no exemptions and failure to comply could impact delivery for other parts of the University: our reputation as a sender is predicated on email we send not being marked as spam by the recipient.
For a short period Gmail will send a message back detailing why a message was rejected. It is paramount that you take action immediately to address that issue: failure to do so could hinder ongoing delivery.
The temporary failure messages include error codes that indicate which sender requirement is causing the failure:
| Error code | Description |
| 4.7.27 | SPF isn’t set up for your sending domains or IP addresses. All senders must use either SPF or DKIM authentication for outgoing messages. Bulk senders must use both SPF and DKIM authentication for outgoing messages. |
| 4.7.30 | DKIM isn’t set up for your sending domains or IP addresses. All senders must use either SPF or DKIM authentication for outgoing messages. Bulk senders must use both SPF and DKIM authentication for outgoing messages. |
| 4.7.23 | Your domain or IP address doesn’t have valid forward and reverse DNS records. This is a requirement for all senders |
| 4.7.29 | Messages aren’t sent over a secure TLS connection. This is a requirement for all senders. |
| 4.7.32 | The domain in the From: header of your messages isn’t aligned with either the SPF domain or the DKIM domain. This is a requirement for bulk senders. |