[Mailman] Error when posting to the mailing list

[Rui Correia]

Greetings,

I've added my email rds_correia at lavabit.com to
talk-pt at openstreetmap.orgmailing list.
All went fine with the registration and with the confirmation to register.
But now when I try to post to the ML I get a message such as this one:

This message was created automatically by mail delivery software.
A message that you sent has not yet been delivered to one or more of its
recipients after more than 48 hours on the queue on offsite2.bytemark.co.uk.

The message identifier is:     1Q9uMM-0000rN-Pq
The date of the message is:    Wed, 13 Apr 2011 08:18:10 +0100
The subject of the message is: =?ISO-8859-1?Q?V=E1rias_quest=F5es?=

The address to which the message has not yet been delivered is:

  talk-pt at openstreetmap.org
<https://lavabit.com/apps/webmail/src/compose.php?send_to=talk-pt%40openstreetmap.org>
    Delay reason: SMTP error from remote mail server after RCPT
TO:<talk-pt at openstreetmap.org
<https://lavabit.com/apps/webmail/src/compose.php?send_to=talk-pt%40openstreetmap.org>>:
    host a.mx.openstreetmap.org [89.16.179.150]: 451 Could not complete sender
verify callout

No action is required on your part. Delivery attempts will continue for
some time, and this warning may be repeated at intervals if the message
remains undelivered. Eventually the mail delivery software will give up,
and when that happens, the message will be returned to you.


What should I do?
The 1st post I did was more than 48 hours ago.

Regards,

Rui Correia
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