Hi all.

(Apologies if this is in the wrong forum - this is the closest I could get to where I thought it belongs)

We're (as a business, a large multinational power company) pretty new to emails. Due to the nature of our documentation, if an email version fails, we're obliged to send a paper copy to the registered address.

Our current system will issue a paper copy as soon as any SMTP code is returned by our mail server. This is becoming wasteful, as the customer will often receive the email version followed by a paper copy; temporary delays to emails means we trigger the paper copy before it's confirmed the electronic version failed.

We're trying to work out how to better handle this based on the returned SMTP codes. Some have suggested that we should send paper copy after receiving a 5xx SMTP code; others have positied that there fatal 4xx codes and that the current system is appropriate, irrespective of the waste.

Does anyone have a resource/guide to handling this please? I'd like to work out how best to ensure the customer receives only one copy of the communication - i.e. only send the paper copy when we can be absolutely certain the email has failed.

Many thanks in advance,

Tom Denyer