Handling SMTP e-mail errors
When configured to use SMTP, iHub categorizes errors that occur when sending e‑mail messages as either retryable or non-retryable. iHub supports resending e‑mail messages when a retryable e‑mail error occurs.
If a cluster node receives an error when sending an e‑mail message to an SMTP server, it sends the e‑mail message using the next configured SMTP server. If the node that sends the e‑mail message receives non-retryable errors when sending the e‑mail message to all SMTP servers, it writes a message to the error log.
If the node that sends the e‑mail message receives an error from all the SMTP servers, and at least one of the errors is a retryable error, the node waits for the retry interval of one second and tries to send the message to the SMTP server that returns a retryable error. If the SMTP server returns an error again, the node writes a message to the error log.
If iHub receives one of the following types of errors, it attempts to resend the e‑mail message:
Cannot connect to SMTP server
Network connection fails
Wait for response times out while sending message
For each error iHub receives, it writes a message to the diagnostic log.
If iHub receives one of the following types of errors, it does not attempt to resend the e‑mail message:
Unrecognized recipient
Message too large
Message contains too many recipients