Send email by setting "from" address causing unverified sender

 

Understanding "Unverified Sender" Issues

An "unverified sender" message usually indicates that the email server or recipient has detected that the email was sent from a source that does not have proper authentication or authorization to send on behalf of the specified domain. This can lead to emails being marked as spam or rejected entirely.

Steps to Resolve "Unverified Sender" Issues

1. Configure SPF (Sender Policy Framework)

SPF helps email receivers verify that the sender’s IP address is authorized to send email on behalf of the domain.

1. Create an SPF Record:

   • Access your domain's DNS settings.
   • Create a new TXT record with the following format:

     makefile
     
     v=spf1 include:_spf.yourdomain.com ~all
     

     Replace _spf.yourdomain.com with your email service provider’s SPF record.

2. Add Authorizations:

   • Include IP addresses or domains authorized to send emails on behalf of your domain. For example:

     makefile
     
     v=spf1 ip4:192.0.2.0/24 include:_spf.google.com ~all
     

3. Publish the SPF Record:

   • Save and publish the record in your DNS settings.

4. Verify SPF Record:

   • Use an SPF checker tool like MXToolbox to verify that your SPF record is correctly configured.

2. Configure DKIM (DomainKeys Identified Mail)

DKIM allows the email to be signed with a private key, which is verified by the receiver using a public key published in DNS.

1. Generate DKIM Keys:

   • Use your email service provider’s tools to generate a DKIM key pair (public and private keys).

2. Create a DKIM Record:

   • Add a TXT record to your DNS with the public key. The format is usually:

     arduino
     
     selector._domainkey.yourdomain.com   IN   TXT   "v=DKIM1; k=rsa; p=YOUR_PUBLIC_KEY"
     

3. Enable DKIM Signing:

   • Configure your email server to sign outgoing emails with the DKIM private key.

4. Verify DKIM Configuration:

   • Send a test email and check the DKIM signature using tools like DKIMCore or MXToolbox.

3. Implement DMARC (Domain-based Message Authentication, Reporting & Conformance)

DMARC helps prevent unauthorized use of your domain by specifying how receivers should handle emails that fail SPF or DKIM checks.

1. Create a DMARC Record:

   • Add a TXT record to your DNS with the following format:

     css
     
     _dmarc.yourdomain.com   IN   TXT   "v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com"
     

     Replace the email address with one where you want to receive reports. The p tag defines the policy (none, quarantine, or reject).

2. Set DMARC Policy:

   • Start with a policy of none for monitoring. Later, you can change it to quarantine or reject to enforce policies.

3. Publish and Monitor:

   • Publish the DMARC record and monitor the reports to understand how your emails are being processed.

4. Adjust Policies:

   • Gradually move to stricter policies (quarantine or reject) based on the monitoring results.

4. Configure Reverse DNS (PTR Records)

Reverse DNS ensures that the IP address of your mail server resolves to your domain name.

1. Set up Reverse DNS:

   • Contact your ISP or hosting provider to set up a PTR record for your mail server’s IP address pointing to your domain.

2. Verify Reverse DNS:

   • Use tools like MXToolbox to verify that the reverse DNS is correctly set up.

5. Ensure Proper Email Headers and Authentication

• Check Email Headers:

  • Ensure that your emails have proper headers, including From, Reply-To, and Return-Path.

• Enable Authentication:

  • Use authenticated SMTP to ensure that emails are sent through a verified process.

6. Monitor Blacklists

Regularly check if your domain or IP address is listed on email blacklists and take steps to delist if necessary.

1. Use Blacklist Check Tools:

   • Use services like MXToolbox to check if you are blacklisted.

2. Remove from Blacklists:

   • Follow the procedure to remove your domain/IP from any blacklists found.

Example DNS Records for Email Authentication

Here’s an example of what your DNS records might look like for a properly configured domain:

SPF Record:

arduino

yourdomain.com   IN   TXT   "v=spf1 include:_spf.google.com -all"

DKIM Record:

arduino

selector._domainkey.yourdomain.com   IN   TXT   "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCz..."

DMARC Record:

css

_dmarc.yourdomain.com   IN   TXT   "v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com"

Summary

By configuring SPF, DKIM, and DMARC records, ensuring reverse DNS is set up, and maintaining good email practices, you can resolve "unverified sender" issues and improve your email deliverability. Regular monitoring and adjustments based on feedback and reports will keep your email system compliant and effective.