my mailbox has a problem,when i was send a mail to @lcenter.fr,it's alawys show code 421 failed to send.

    when i used gmail do this,i will receive a authentification letter from @lcenter,This email signed from "mailinblack"

    After clicking on a link authentication, I can send him an email.

    But I can't send this email with Zoho, and I can't accept it.