550 Error, Recipient address rejected

[1929flows]

Dear community,

I need your help! Since 2 weeks my school cannot send any messages anymore, because of this error: SMTP Error (550): Failed to add recipient "[email protected]" (5.1.1 <[email protected]>; Recipient adress rejected: yahoo.de).

We can not send messages anymore, nor reply. I would greatly appreciate your help.

Kind regards,

Carlo

[JohnDoh]

That error is coming from your SMTP server so you need to contact your email provider for help. It could be you need to configure SMTP authentication in Roundcube.

[crasheg]

Chek your server IP in spam lists.