Talk to our team

Documentation

✉️ Email Delivery

Documentation, reference material and tutorials for CRM-NG SMTP Email: setup guides for every mail service, troubleshooting, and one article per error message.

Error: 550 Requested action not taken: address does not exist or was rejected

Updated

By Duane GarnerChief Executive Officer (CEO)
Summarize: Claude ChatGPT View Markdown
On this page

The server permanently refused the message for this recipient: the mailbox does not exist, relaying was denied, or a policy blocked it.

Shown by SMTP-based sending (Other SMTP, Zoho Mail, the backup SMTP transport)

The test result or the error log shows a reply starting with 550, for example 550 5.1.1 User unknown, 550 5.7.1 Relaying denied or 550 Requested action not taken: mailbox unavailable.

This article is for site owners sending through an SMTP server who get a 550 reply. CRM-NG SMTP links here for any 550 that is not a "host unknown" reply.

What this error means

Reply code 550 is a permanent refusal. The server will not take this message, and sending it again unchanged will fail the same way. The detail code after 550 tells you why:

  • 5.1.1 and similar: the recipient's mailbox does not exist.
  • 5.7.1 "relaying denied": the server will not pass mail on for you, usually because you are not logged in.
  • 5.7.x with words like "spam", "policy", "SPF" or "DMARC": the message or sender failed a check.

Common causes

  • A typo in the recipient address, or a mailbox that has been closed.
  • Authentication is off in CRM-NG SMTP, so the server treats you as a stranger and refuses to relay to outside domains.
  • The From Email domain fails SPF or DMARC, so the recipient's server rejects it.
  • Your server's IP or your provider's IP is on a blocklist used by the recipient.
  • The recipient's server considers the content to be spam.
  • The recipient's mailbox is full and the server reports that permanently.

How to fix

  1. Read the full reply

    Open the error in CRM-NG SMTP → Tools → Debug Events and note the detail code and wording.

  2. For unknown users: fix the address

    Check the spelling and confirm with the recipient. Update it in the plugin, form or user profile that sent the email.

  3. For relaying denied: log in

    Go to CRM-NG SMTP → Settings → General. Turn on Authentication and enter SMTP Username and SMTP Password. Save.

  4. For policy rejections: fix authentication

    Publish SPF, DKIM and DMARC for the domain in From Email, as your mail provider describes. Turn on Force From Email so every message uses that domain.

  5. For blocklists

    Check your sending IP on a public blocklist checker. Ask your mail provider or host to help with delisting.

  6. Send a test

    Go to CRM-NG SMTP → Tools → Email Test, fill in Send To and press Send Email.

Verify it worked

The test page shows "Test email sent successfully! Check your inbox to confirm delivery." Check the Deliverability and domain authentication results on the same page for SPF and DMARC.

Notes

  • Repeated sends to addresses that do not exist hurt your sending reputation. Remove dead addresses from lists and user records.
  • The backup SMTP transport never retries permanent recipient errors.
Go to Top