Initial situation:
After receiving an email, the SEPPmail Secure E-Mail Gateway should confirm the successful receipt to the sending relay ("250 ok") only once this email has already been acknowledged as successfully received by the following relay (also "250 ok").
Reason:
If this option is used, it can be practically ensured that no emails are lost when the appliance is replaced (e.g. in the event of a hardware defect).
Solution:
Up to SEPPmail Secure E-Mail Gateway version 11.1.11, the option Queueless mode was available for this purpose. In version 11.1.11, this was replaced by the new option Use custom delivery method. Through the entry "queueless", this option achieves the same behaviour as previously achieved by Queueless mode.
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This setting can cause delays, especially if the email processing machines are located in different networks. One consequence of this can be increased timeouts. Furthermore, the temporary caching of an email in the email queue cannot be 100% prevented by this setting: •If, for example, several email domains are addressed for outgoing emails, one of which does not acknowledge receipt with the SMTP code 250, the email to this one email domain will still be cached in the email queue. •If the subsequent email HOP fails completely, the appliance will also store the emails in the queue and thus acknowledge receipt to the delivering system. •Likewise, LFT notification emails are cached in the queue if the recipient is temporarily unavailable.
It is also important to note that with this setting, any smarthost entered in a Managed domain is ignored. Instead, the globally entered outgoing server from Use The Following SMTP Server is always used. The setting Use Built-In Mail Transport Agent is incompatible with the Queueless mode and would therefore produce the message "Could not retrieve default mail routing information - queueless mode disabled" in the log. |
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In the update, the setting from Queueless mode is automatically adopted into the new option Use custom delivery method (entry "queueless"). |
