sparrowdesk-logo-transparent-1.png
Go to sparrowdesk.com
Home
SparrowDesk Overview
  • Overview of SparrowDesk
  • Feature Overview in SparrowDesk
  • SparrowDesk Glossary
Getting Started
  • Setting Up Account Details
  • Default Business Hours
  • Understanding and Creating Teams
  • Inviting Team Members to the Platform
  • Roles and Permissions
  • Single Sign-On
  • Brands in SparrowDesk
  • Getting Started FAQs
  • Use a custom domain for your support portal
Inbox
  • Understanding the Inbox in SparrowDesk
  • Managing Custom Views in Inbox
  • Live Chats in Inbox
  • Staying on Top of New Messages from Customers
  • Conversation Fields in SparrowDesk
  • Merging Conversations in SparrowDesk
  • Adding Watchers to a conversation
  • Round Robin assignment explained
  • Export Conversations as CSV
  • Bulk update fields
  • Forward a Conversation to an External Contact
  • Common Email Delivery Errors
Channels
  • Setting Up Email as a Support ChannelConnect your custom email address How do I send and receive emails via SMTP and IMAP ? How do I find my SMTP/IMAP server address and port number? Common Errors while Connecting through SMTP/IMAPHow to Prevent Emails From Going to Spam Email Signatures
  • Installing Chat Widget Chat Widget Installation on WordPressInstall the Chat Widget on ShopifyCustomising Chat WidgetEmbedding and Configuring the SparrowDesk Chat WidgetChat Widget SettingsWhy End Users Don’t Always See Their Chat HistoryTrack page visits in SparrowDesk
Contacts
  • Contacts in SparrowDesk
  • How to manage contact segments
  • Deleting and Blocking Contacts in SparrowDesk
  • Contact Fields in SparrowDesk
Reports
  • Conversation Report
  • Team Performance Report
  • Understanding the AI Agent Report in SparrowDesk
  • Viewing CSAT reports in SparrowDesk
  • Reports FAQ
  • Exporting Reports as PDF
Automation
  • Macros
  • Business Hours
  • Service-Level Agreements (SLAs)
  • Setting up CSAT (Customer Satisfaction) in SparrowDesk
Zoona AI
  • AI Suggested replies in your Inbox
  • AI-Generated Chat Subjects
  • Zoona AI Knowledge Improvements
  • Introduction to AI AgentAI Agent - Configure PersonaTraining your AI AgentZoona AI Agent CommandsAI Agent - Deploying on chatAI Agent - Deploying on EmailHow to Create a Command Zoona AI Agent - FAQUnderstanding AI resolutions in SparrowDesk
Workflows
  • Automate repetitive tasks through Workflows
  • How to Create a Workflow
  • Workflow Blocks Library
Help Centre
  • Write Knowledge Articles for your Help Centre and AI Agents
  • Setting Up and Customizing Your Help Center
  • Use a Custom Domain for Your Help Center
  • Make Your Help Centre Discoverable in Search results
  • Adding Google Tag Manager to your Help Center
  • Creating a Ticket Form Setting up Customer Portal
Billing
  • How does SparrowDesk pricing work?
  • What is Seat ?
  • Manage your Billing and Invoices
  • About Sales Tax
  • How to cancel your subscription
  • Frequently Asked Questions
  • AI Co-pilot and AI Resolution billing
  • SparrowDesk Startup Program
Apps and Integrations
  • Okta Single Sign on setup for SparrowDesk
  • Integrating HubSpot with SparrowDesk
  • Integrating SurveySparrow with SparrowDesk
  • Integrating SparrowDesk with Zapier
  • Connecting SparrowDesk with Attio
  • Connecting SparrowDesk with Linear
  • Integrating SparrowDesk with Jira
  • Connecting SparrowDesk for Gmail
  • Integrating SparrowDesk with Notion
  • Integrating SparrowDesk with Slack
  • Integrating SparrowDesk with Shopify
  • Connect WhatsApp to SparrowDesk

Common Email Delivery Errors

Timer4 min read
ShaikShaik

Why did a message delivery fail from the Inbox?

Troubleshoot common email delivery errors when a reply fails to send from the SparrowDesk Inbox.

When you send an email reply from the SparrowDesk Inbox, the message may occasionally fail to deliver. This usually happens because the recipient’s email address, mailbox, or email provider rejected the message.

When this happens, SparrowDesk shows a delivery failure note inside the conversation. The note helps your team understand which email address could not receive the reply and why the delivery failed.

image.png
In most cases, these errors come from the customer’s email provider. For example, the customer’s mailbox may be full, the email address may no longer exist, or their mail server may have blocked the message.

You can try sending the reply again later, contact the customer through another email address, or use another available channel.

Delivery failure notes do not reopen closed conversations automatically.

Common delivery errors

Here are some common email delivery errors and what they usually mean.

Error code

What it means

What you can do

421-4.7.28

The recipient’s provider temporarily deferred the email. This can happen when the provider detects unusual sending activity or rate limits messages from a domain.

Try sending again later. Make sure your sending domain is properly authenticated with SPF and DKIM.

550

A general delivery failure. This can mean the email address does not exist, the message was blocked, the mailbox is full, or the recipient’s provider rejected the email.

Check the full error message for more details. Verify the customer’s email address and try another contact method if available.

550-5.1.1

The email address is invalid or no longer exists. It may also happen if there is a typo in the customer’s email address.

Confirm the customer’s email address and update the contact before sending again.

550-5.7.1

The message was rejected because of a security, spam, authentication, or policy rule on the recipient’s side.

Check that your sending domain is authenticated. Ask the customer to check whether their email provider or IT team is blocking your messages.

552-5.2.2

The recipient’s mailbox is full and cannot receive new messages.

Try again later or contact the customer through another channel.

554-5.4.4

The recipient’s mail server could not route or deliver the email. This may be caused by DNS issues, server configuration, or network restrictions.

Try again later. If the issue continues, ask the customer to check their mail server settings.

554-5.4.7

The message could not be delivered after repeated attempts. This may be caused by routing issues, temporary server problems, or provider restrictions.

Try again later or use another email address/channel if available.

Email address is on a bounce list

If an email address repeatedly fails with a permanent delivery error, it may be added to a bounce or suppression list. This prevents future emails from being sent to that address and helps protect your email sending reputation.

Before requesting removal from a bounce list, make sure the original issue has been fixed. For example:

  • The email address is valid.
  • The mailbox is no longer full.
  • The customer’s mail server is accepting messages.
  • Your sending domain is authenticated correctly.

If you believe the address is valid and the issue has been resolved, contact SparrowDesk support for help.

Troubleshooting message delivery failures

If you see a message failed error inside the Inbox, first try sending the message again.

If the error continues:

  1. Check whether the contact email address is correct.
  2. Confirm that the conversation is still active.
  3. Make sure your support email is connected and verified.
  4. Check whether your sending domain authentication is set up correctly.
  5. Try contacting the customer through another available channel.

If the issue still isn’t resolved, contact SparrowDesk support with the conversation link and the error message shown in the Inbox.

Best practices to reduce delivery failures

To improve email deliverability from SparrowDesk:

  • Use a verified support email address.
  • Set up SPF and DKIM for your sending domain.
  • Avoid sending repeated replies to invalid email addresses.
  • Keep customer email addresses updated.
  • Use another channel when an email repeatedly fails.
  • Ask customers to whitelist your support email if messages are being blocked.

Need more help?

If delivery failures continue, reach out to [email protected] with:

  • The conversation link
  • The customer email address
  • The error code or failure message
  • The time the message was sent

This helps the support team investigate the issue faster.

Powered By SparrowDesk

Table of ContentsOn this page