Message d'erreur 5.5.1

[Ednafp]

Sending mailing ... about 10% left to be sent ... (140) and it is blocked with this message : 5.5.1 what does it mean and how do I bypass the problem ?
Thank you ....
:roll:
EFP

 

[stanbusk]

Please paste the line with the 10 or so before it to see the context.