Zoho

Zoho is a range of online services for businesses. It includes an email hosting product with spam filtering, firewall, and block list features.

Domains

zoho.com

Codes

451 · 452 · 550 · 552 · 553 · 554

451
541 5.4.1 Mail rejected by destination domain

Zoho allows the receiving domain to set mail filters. The receiving domain has filters set-up that are blocking this message. To resolve this, you'll need to contact an administrator of this domain through another channel to have them adjust their filters and allow delivery.

452
452 <example@zoho.com> Mailbox delivery restricted by policy error

Zoho allows the receiving domain to set mail filters. The receiving domain has filters set-up that are blocking this message. To resolve this, you'll need to contact an administrator of this domain through another channel to have them adjust their filters and allow delivery.

452 4.3.1 Temporary System Error

This indicates that the domain at Zoho is not currently accepting email. Sending messages again in the future will most likely be successful.

550
550 5.7.1 Email rejected per DMARC policy for zoho.com

This is related to using a zoho.com address from an external service or app without the Zoho SMTP settings in those apps.

550 5.1.1 <example@zoho.com> User unknown
552
552 5.1.1 <example@zoho.com> Mailbox delivery failure policy error
552 5.7.1 virus [name] detected by Zoho Mail

A known virus was detected in your message content, attachments, and/or URLs. Run the full message and its headers through a virus scanner to identify the source.

553
failed,5.1.1 (bad destination mailbox address),553 Relaying disallowed,mx.zoho.com
554
554 5.2.3 MailPolicy violation Error delivering to mailboxes,mx.zoho.com

Reasons for this response vary significantly, so the best place to start is the Zoho Community forum.

554 5.7.1 Email cannot be delivered. Reason: Email flagged as Spam.