On Mon, 10 Apr 2006 15:40:44 EDT, "Gartner, James" said:
> Folks,
> What is the difference between a BOUNCE, and a SOFTBOUNCE in a bounce
> report??
> For example:
> 20060406103345 BOUNCE [log in to unmask] 5.1.1 Mailer vaemail2.abc.com
> said:            "550 5.1.1 <[log in to unmask]>... User unknown"
> 20060406103626 SOFTBOUNCE [log in to unmask] 5.3.0 553 5.3.0
> <[log in to unmask]>... Unknown user - sorry. 

A BOUNCE is, in SMTP parlance, the response from a "permanently failed" attempt
that will in all likelyhood *not* succeed until a human takes manual
intervention (for instance, a "no such user" error, end user mailbox full, or a
permanent permissions issue on a mailbox).

A 'Soft Bounce' is a *temporary* failure that has a high chance of succeeding
if retried - network outages, full spool disks on the inbound receiving area,
excessive mail server load, and so on...

Having said that, I'm not clear why your example got flagged as a 'softbounce' -
usually failures have 5XX and 5.y.z errors, while temp fails have 4XX and 4.y.z
codes (in fact, the 4/5 distinction is defined as how to tell one from the other).