Sending successfully to Terra and reaching the inbox is highly dependent on your sending reputation and following sending best practices. While following best practices doesn’t guarantee inbox placement at Terra, it greatly increases your chances for success.
One of the best ways to reach the inbox at Terra, is sending relevant content that your subscribers want to receive. Low complaint rates and having subscribers marking your email as “not spam” signals to Terra that you are less likely a spammer.
- Ensure all sending IP addresses have a non-generic, unique reverse DNS (PTR) record.
- Enroll all sending IP addresses in the Terra complaint feedback loop and add all complainers to a suppression list. Complaints are the main cause of mail being delivered to the spam folder.
- Do not send bulk email from a dynamic IP address.
- Ensure you send content free of viruses and spyware.
- Ensure your sending system is secured against unauthorized access such as an open relay.
- Have a bounce process in place and remove unknown users after one bounce. Although Terra tolerates an unknown user rate up to 10%, senders that achieve consistent success reaching the inbox at Terra maintain a low unknown user rate of 1% or below.
- Respect Terra’s resources and do not open an excessive number of connections to their servers. Monitor your soft bounces (4XX) for error codes indicating throttling and decrease the number of connections and throughput until the bounces are no longer received.
- Although Terra does not publish connection and throughput information, some senders have had success using 2 simultaneous connections with 50 messages per connection and adjusting the configuration based on the SMTP error code feedback from Terra. The connection limit varies according to the load on their servers, so these settings may need adjustment during high volume sending times such as a major holiday.
- Authenticate all email with Domainkeys Identified Mail (DKIM) and Sender Policy Framework (SPF). Messages failing SPF authentication verification are blocked by Terra.