MailChannels helps ensure safe email delivery by blocking spam and enforcing sending policies. When emails fail, you may see an error code, and these may seem intimidating, but each one has a clear meaning and a fix. By understanding MailChannels error codes, what they mean and applying the right steps, such as cleaning mailing lists, enabling SPF/DKIM/DMARC, or avoiding spam-like content, you can resolve most issues quickly and improve your sending reputation.
This guide will help you decipher common error codes and how to fix them.
Common MailChannels Error Codes and Fixes
550 5.7.1 [CS] Message Blocked – Spam
What This Error Means
Your message was detected as spam and blocked. A non-delivery report is sent with the reason.
How to Fix
- Review the message for spam-like content or formatting.
- If this was a false positive, contact 1-grid Support to log a request with MailChannels.
550 5.7.1 [ESA] Sender Blocked Error
What This Error Means
Abuse was detected from your account. This could include:
- Spam or bulk email
- High complaint rates
- Large numbers of invalid recipients
How to Fix
- Change your password (use at least 8 characters with a mix of upper/lowercase, numbers, and symbols).
- Update your operating system with the latest security patches.
- Run a full scan with up-to-date antivirus software to check for malware.
550 5.7.1 [RBL] Sender Blocked – Blacklist
What This Error Means
Your domain or IP is listed on a global blacklist (e.g., Spamhaus).
How to Fix
- Check the IP or domain listed in the error against RBLs (use tools like Spamhaus Domain Lookup Tool).
- If listed, request delisting directly from the blacklist provider.
550 5.7.1 [CS] Virus Detected in Message
What This Error Means
An outgoing email from your account contains a virus.
How to Fix
- Change your password immediately.
- Update your operating system with the latest security updates.
- Update antivirus software and run a full system scan.
- If the problem persists, contact 1-grid Support.
550 5.7.1 [IRR] Too Many Invalid Recipients
What This Error Means
Your account sent emails to too many invalid addresses, harming your sending reputation.
How to Fix
- Clean your mailing list using verification tools (e.g., VerifyEmailAddress.org, MailTester.com).
- Follow best practices:
- Use double opt-in to confirm valid addresses.
- Remove invalid recipients immediately.
- Send only to contacts who subscribed to your list.
- Once the list is cleaned, you’ll be able to send emails again automatically.
550 5.7.1 [HIC] Abuse Detected
What This Error Means
Abusive behaviour was detected from your account, often due to a compromise.
How to Fix
- Change your password immediately (strong, unique format).
- Ensure your operating system has the latest updates.
- Update antivirus software and run a full system scan to remove any malware.
Preventing MailChannels Errors
- First, set up SPF, DKIM, and DMARC to authenticate your email.
- Next, use clean, verified mailing lists only.
- Then, monitor bounce rates and remove invalid addresses.
- In addition, avoid spam-like subjects and heavy attachments.
- Finally, limit sending volume to avoid throttling.
When to Contact 1-grid Support
If errors persist even after trying these solutions, reach out to 1-grid Support.
Provide the following (with screenshots, where possible):
- The full bounce-back message.
- Steps you’ve already taken.
- A copy of your SPF/DKIM/DMARC records for review.
FAQs
Do all MailChannels errors mean my domain is blacklisted?
No, many are temporary or content-related. Blacklisting is rare but possible if sending practices violate policies.
Can MailChannels errors affect only Gmail?
While Gmail is stricter, MailChannels applies policies across all providers.
How do I avoid “too many invalid recipients” errors?
Regularly clean your mailing lists and use confirmed opt-ins.
Will enabling DKIM and SPF fix all errors?
No, as while they prevent many issues, practicing sending best practices also matter.
What’s the difference between a temporary and permanent error?
Temporary errors (421, 451) resolve on retry while permanent ones (550, 554) need action before resending.
Additional Resources
Blocked via Mailchannels Due to Spam
How to Avoid MailChannels Blocks
How to Resolve MailChannels Error 550 “Too many invalid recipients”
Top 10 Common Email Issues and How to Resolve Them
Setting Up Email in Outlook via Windows Control Panel
How to Set Up Email on Android for Your 1-grid Email Accounts
Settings to Configure Your 1-grid Email Accounts Across Devices
Resolving Email Error Messages When Sending to Gmail Accounts
What is IP Blacklisting?
How Do I Check if My IP is Blacklisted?
SpamTitan: How to Blacklist an Email Address or Domain
What Is Email Spoofing? How It Works and How to Protect Yourself
How to Spot a Scam Email
Email Headers FAQs
Email FAQs
How to Enable DKIM and SPF on Your Mail Domain
Why SSL? The Purpose of Using SSL Certificates
What is a Domain Name Server (DNS)?
How to Update Your Domain’s Nameservers at 1-grid
MailChannels FAQs
SpamTitan FAQs
Need Additional Support?
We’re Here to Help:
Understanding MailChannels error codes and how to resolve them doesn’t have to feel technical with this easy-to-reference guide. Stuck? Contact our Support Team for clarity and guidance (https://1grid.co.za/contact-us/). We’re ready to see how we can help!