Hi,
We are observing the same bounces, but things seem to be improving since
11:41 a.m. (CEST).
Best,
Pierre-Yves Dubreucq

On Thu, Feb 12, 2026 at 10:33 AM Hans-Martin Mosner via mailop <
[email protected]> wrote:

> Am 12.02.26 um 10:03 schrieb Stefano Bagnara via mailop:
>
> Hi all,
>
> I didn't read news about it, but I see bogus "550 Invalid domain" replies
> to MAIL FROM from many IP/domains when sending email to libero.it since
> 11/2/2026 16:00 CET (the transaction hangs some seconds in the mail from
> and then returns the invalid domain error).
>
> I confirmed the issue also sending from a consumer gmail inbox: I got a
> bounce "550 Invalid domain".
>
> They probably have DNS issues and incorrectly configured SMTP handling of
> DNS failures. Any failures (except for explicit NXDOMAIN responses) should
> IMHO lead to temporary rejections (4xx codes), not permanent rejections
> such as 550.
>
> As we don't have much interaction with italian contacts, I did not see
> that error on our mail systems.
>
> Cheers,
> Hans-Martin
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