Your message wasn't delivered because the recipient's email - Microsoft Community

hello,

this error message continues come time time office 365 users i'm working in rwanda, , i'm having trouble addressing it.  message indicates recipient's email provider rejecting message, in case, same bounceback multiple recipients in various domains.  users experiencing issue migrated office 365 google apps if makes difference. 

diagnostic information administrators:

generating server: am4p191mb0019.eurp191.prod.outlook.com

[email address]
remote server returned '550 5.7.501 service unavailable, client host blocked using spamhaus. request removal list see http://www.spamhaus.org/lookup.lasso (as16042849)'

if sender's ip addresses spamhaus, show in pbl, when read further means, sounds personal / dynamic ips should there, think acting expected. 

any ideas why occurring? 

thanks!

chris

hi chris,

in situation, i suggest use administrator account( if not admin, involve admin )to log into exchange admin center. and click protection> action center to check if blocked. here article reference:

removing user, domain, or ip address block list after sending spam email.

if admin delisted user no avail, further analysis, please provide tenant information , whole ndr via the private message.

thanks,

amanda

Office / Office 365 for admins / Exchange Online / Office 365 for business