la greylist de l'imag

bonjour a tous,

quand je poste, mon message arrive au bout de 10mn car le serveur de l'imag me
met en deferred:

to=<guilde@???>, delay=00:03:25, xdelay=00:00:02, mailer=esmtp,
pri=121808, relay=imag.imag.fr. [129.88.30.1], dsn=4.7.1, stat=Deferred: 451
4.7.1 Greylisting in action, please come back in 00:06:37

puis automatiquement au bout de dix minutes:

to=<guilde@???>, delay=00:28:25, xdelay=00:00:02, mailer=esmtp,
pri=211808, relay=imag.imag.fr. [129.88.30.1], dsn=2.0.0, stat=Sent
(i9KE9H5D020662 Message accepted for delivery)

comment corriger cela ?

Stephane