SMTP Guidelines

There are a number of guidelines regarding SMTP:

• Realiability
• Security
• Maintainability
• Performance
• Fair use

Reliability

1. Messages that are submitted to Spotler SendPro will be confirmed by a 250 Queued xxxxxxxxxxxxxxxxxxxxxx response. Only when this response is received, a source system should assume the message will be handled by SendPro.
2. In any system integration, eventually individual connections/message submit will fail. To prevent loss of messages, a retry mechanism, preferably backed by a queue system, is required.
3. The SendPro SMTP service can be reached by multiple IP addresses. Retries should be preferably done to different IP addresses to maximize availability.

Security

1. Always use STARTTLS or TLS connections and check the validity of the offered certificate.
2. Use separate credentials for different source systems and instances. Also, make sure these credentials have their minimum required role assigned; i.e. you don't need Admin privileges to submit messages.

Maintainability

1. Your client should accept any valid certificate if a trustworthy chain can be established. Please do not register the current certificate in use, to prevent problems when it's replaced.
2. Our service IP addresses change rarely, however, please connect using our DNS names and configure your environment to adhere to DNS record changes.

Performance

1. Any oAuth2 tokens are valid for multiple requests. Please use them for as long as they're valid, especially in batch processes.
2. Optimize sending multiple messages using a single connection. Establishing TLS connections is relatively slow and should be avoided.
3. Enable Pipelining if possible.
4. If you need more performance and eliminate the effects of latency, please feel free to connect up to 10 times concurrently per client IP.

Fair use

1. Avoid unnecessary load and unused connections.