On 14/01/15 20:10, Robert Blayzor wrote: > When using LTMP transport for delivery, what happens if LMTP kicks back an error condition to Exim? For instance in the following LTMP conversation: [...] > What exactly happens? Is a SMTP error (4xx or 5xx) generated back to the sending MTA or is it to late by then?
Generally MTAs operate in store-and-forward fashion, so it is too late
for this MTA to emit an error on the source SMTP conversation.
> If it's too late to return an SMTP error, does Exim handle the 4xx and 5xx at LMTP differently? Meaning a 5xx would generate a bounce and a 4xx would be queued for later delivery attempts?