Managing network issues
Network issues are a fact of life. In particular, there are no quality of service guarantees for connections over the Internet, and it is important that your systems are able to manage network difficulties.
If you follow our recommendation to use a local SMTP forwarder as the outgoing message interface between your application servers and the Contactsend SmartRelay injection point, you already have an appropriate solution. Outbound messages are stored for dispatch later, without disrupting your applications when, for example, connectivity issues occur, or maintenance is being carried out.
In a similar way, if you exceed the SmartRelay inbound rate limit and your message flow is temporarily throttled, your SMTP forwarder can keep the relevant messages in its local storage and retry later.
Otherwise, if for whatever reason, you do not want to use an SMTP forwarder, you need to set up some other local, storage-capable, queue-based system for your applications to use.