[Troubleshooting] How to troubleshoot mail server marked as spam
1. The cause was listed as IP blacklist
Normally, during the using process, your public IP is often marked as spam on the blacklist by Spam mail Prevention organization. Therefore, your sent mails from your server will be listed as spam mails (or junk mails) by Google, Yahoo, ect… Even in some cases, mail services such as Gmail, Yahoo, Outlook can be dropped your mail from the server immediately and the email is not be delivered.
These are usual causes:
• The email server at this IP address contains a virus and has been sending out spam.
• Compromised email accounts that someone may be using to send spam.
• The email server at this IP address may be configured incorrectly.
• The PC at this IP address may be infected with a virus or botnet software program.
• An individual in the organization at this IP address may have a PC infected with a virus or botnet program.
• This IP address may be a dynamic IP address which was previously utilized by a known spammer.
• The marketing department of a company at this IP address may be sending out bulk emails that do not comply with the CAN-SPAM Act.
• This IP address may have a insecure wireless network attached to it which could allow unknown users to use it's network connection to send out bulk email.
• In some rare cases, your recipients' Barracuda Spam Firewall may be misconfigured.
• Administrator-set policies for your email.
Example: Why messages are marked as Spam
- Terms of Google:
https://support.google.com/mail/answer/1366858?hl=en
- Terms of Yahoo:
http://help.yahoo.com/kb/index?locale=en_US&page=content&y=PROD_MAIL_ML&locale=en_en&id=SLN3435
- Terms of Hotmail:
http://mail.live.com/mail/policies.aspx
2. How to troubleshoot
- Restrict email with wordy content and too many images.
- Contact the ISP to create a PTR record pointing to your domain.
- Direct contact with the mail server to remove the server IP from blacklist:
+ Google: https://support.google.com/mail/contact/msgdelivery
+ Yahoo: http://help.yahoo.com/l/us/yahoo/mail/postmaster/bulkv2.html
+ Hotmail: https://support.live.com/eform.aspx?productKey=edfsmsbl3&ct=eformts&scrx=1
- Remove the IP from the blacklist of Spam Prevention organizations:
+ PBL Spamhaus: http://www.spamhaus.org/pbl/removal/form/ (Yahoo used this database)
+ CBL Spamhaus: http://cbl.abuseat.org/lookup.cgi
+ Barracuda: http://www.barracudacentral.org/rbl/removal-request
+ SpamRats: http://www.spamrats.com/removal.php
+ MXToolbox: http://www.mxtoolbox.com/blacklists.aspx
- Confirm that your DNS is set-up correctly: add MX PTR, SPF, DKIM record for your domain.
- Some notes to configure the SMTP server:
+ Turn off the “Relay” function on the SMTP server to prevent sending email with spam purpose.
+ Limit the number of sent emails at once.
Example: Microsoft recommendations
http://mail.live.com/mail/troubleshooting.aspx
Normally, during the using process, your public IP is often marked as spam on the blacklist by Spam mail Prevention organization. Therefore, your sent mails from your server will be listed as spam mails (or junk mails) by Google, Yahoo, ect… Even in some cases, mail services such as Gmail, Yahoo, Outlook can be dropped your mail from the server immediately and the email is not be delivered.
These are usual causes:
• The email server at this IP address contains a virus and has been sending out spam.
• Compromised email accounts that someone may be using to send spam.
• The email server at this IP address may be configured incorrectly.
• The PC at this IP address may be infected with a virus or botnet software program.
• An individual in the organization at this IP address may have a PC infected with a virus or botnet program.
• This IP address may be a dynamic IP address which was previously utilized by a known spammer.
• The marketing department of a company at this IP address may be sending out bulk emails that do not comply with the CAN-SPAM Act.
• This IP address may have a insecure wireless network attached to it which could allow unknown users to use it's network connection to send out bulk email.
• In some rare cases, your recipients' Barracuda Spam Firewall may be misconfigured.
• Administrator-set policies for your email.
Example: Why messages are marked as Spam
- Terms of Google:
https://support.google.com/mail/answer/1366858?hl=en
- Terms of Yahoo:
http://help.yahoo.com/kb/index?locale=en_US&page=content&y=PROD_MAIL_ML&locale=en_en&id=SLN3435
- Terms of Hotmail:
http://mail.live.com/mail/policies.aspx
2. How to troubleshoot
- Restrict email with wordy content and too many images.
- Contact the ISP to create a PTR record pointing to your domain.
- Direct contact with the mail server to remove the server IP from blacklist:
+ Google: https://support.google.com/mail/contact/msgdelivery
+ Yahoo: http://help.yahoo.com/l/us/yahoo/mail/postmaster/bulkv2.html
+ Hotmail: https://support.live.com/eform.aspx?productKey=edfsmsbl3&ct=eformts&scrx=1
- Remove the IP from the blacklist of Spam Prevention organizations:
+ PBL Spamhaus: http://www.spamhaus.org/pbl/removal/form/ (Yahoo used this database)
+ CBL Spamhaus: http://cbl.abuseat.org/lookup.cgi
+ Barracuda: http://www.barracudacentral.org/rbl/removal-request
+ SpamRats: http://www.spamrats.com/removal.php
+ MXToolbox: http://www.mxtoolbox.com/blacklists.aspx
- Confirm that your DNS is set-up correctly: add MX PTR, SPF, DKIM record for your domain.
- Some notes to configure the SMTP server:
+ Turn off the “Relay” function on the SMTP server to prevent sending email with spam purpose.
+ Limit the number of sent emails at once.
Example: Microsoft recommendations
http://mail.live.com/mail/troubleshooting.aspx
