Understanding Long File Name Restrictions in Email Attachments

• Why Was My Email Rejected Due to a Long File Name?

  If you’ve encountered an error when sending an email with an attachment, it may be due to the file name being too long. Our email security platform has measures in place to prevent the delivery of potentially harmful attachments, including those with excessively long file names.

• The Security Risk of Long File Names

  Cybercriminals often use long file names as a tactic to disguise malicious files. They may append multiple extensions to obscure the true nature of the file, such as:

  Example: 12345678910111213141516.pdf.exe

  At first glance, the file may appear to be a PDF, but it is actually an executable (.exe) file, which can contain malware. This technique increases the chances of a user mistakenly opening the attachment and infecting their system.

• How Our Mail Security Handles Long File Names

  To mitigate this risk, our email security system automatically flags and prevents the delivery of attachments with excessively long file names. If your email was rejected due to this reason, the notification details may indicate a message similar to:

  "Securemail: Very long filenames are good signs of attacks against Microsoft e-mail packages."

  This is a precautionary measure to protect your account and ensure a safer email environment.

• What You Can Do to Resolve the Issue

  If your email was blocked due to a long file name, follow these steps:

  1. Shorten the File Name – Rename the attachment to a shorter, more meaningful name related to the content.
     • Example: Instead of fbJGg-0005b6-GW_nFORMPROPS 176.pdf, rename it to Form_Props_176.pdf.
  2. Avoid Special Characters – Remove unnecessary symbols or numbers that may contribute to excessive length.
  3. Resend the Email – Once the file name is adjusted, reattach the document and attempt to send the email again.

  
  

  By following these steps, your message should send successfully without being blocked by our security filters.

• Need Further Assistance?

  If you continue to experience issues after renaming your attachment, please Contact Us for additional troubleshooting.