"User Unknown" errors related to DNS issues?

Mon Dec 13 23:16:20 UTC 2004

On Mon, 13 Dec 2004, Jim Popovitch wrote:

>
> Hi all,
>
> I see a periodic problem with some email servers that report "User
> Unknown" for valid users.  The most recognizable problematic host is
> hotmail.com, but there usually are others mixed in (today's additional
> problematic hosts included msn.com, verizon.net, and incentre.net).
>
> Do others see this same issue?
>

Hi Jim.

I don't think your problem is dns related.
We had problems with many hotmail/msn accounts returning user unknown
for valid users. We tried solving it by resending all email and ignore 550
errors/bounces up to 50 times (several emails were delivered even after 40
550 bounces). Unfortunately hotmail complained about it
after short time because it generated very many bounces.
They suggested signing up for bondedsender.com. Temporary resolved the
problem by still ignoring 550 but up to 15 times and retry in a slower
sequence. We might sign up for bondedsender though.. seems like an okay
idea.

Joergen Hovland ENK