Error sending domains via PHP form.

Error sending domains via PHP form.

Hey guys, when I'm trying to send emails via PHP form using the mail function to my Zoho mail, the server returns the following error:

  1. suporte@seubone.com R=virtual_aliases: No Such User Here

How can I fix that?
Everything seems fine according to MxToolbox, the MailServers are:

10 mx.zoho.com
20 mx2.zoho.com
50 mx3.zoho.com

P.s: I tried the same form with other domains, everything's fine for other domains. It's only happening with seubone.com The same form can send e-mails to Gmail accounts.