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SMTP error code 501 occurs when receiving mails from a long email address

    • Updated:
    • 18 Jan 2016
    • Product/Version:
    • InterScan Messaging Security Suite 7.1 Windows
    • InterScan Messaging Security Suite 7.5 Windows
    • Platform:
    • Windows 2000 Advanced Server
    • Windows 2000 Server
    • Windows 2003 Enterprise
    • Windows 2003 Server R2
    • Windows 2003 Standard
    • Windows 2008 Enterprise
    • Windows 2008 Server R2
    • Windows 2008 Standard
    • Windows 2012 Server Essentials
Summary

The error code 501 appears when InterScan Messaging Security Suite (IMSS) server receives an email from a sender with a long address like the following example:

owner-nolist-MORNING_BRIEF_TEXT-080219O-p70w0se3*PSHELTERS**ERAC*-COM@RETURNS.DOWJONES.COM

Details
Public

The IMSS is designed to comply with the RFC 2821 specifications, which limits the allowed number of characters on the sender's email address. The imposed limit is hard-coded in IMSS program.

As a workaround, disable the IMSS compliance to RFC:

  1. Make sure that the latest Service Pack for IMSS Windows is installed in your machine.
  2. Open the C:\Program Files\Trend Micro\IMSS\config\tsmtpd.ini file using Notepad or any text editor.
  3. Go to [SmtpServer] section and add the following parameter:

    CheckSenderLength=0

     
    A value of "0" disables the sender email address length checking while a value of "1" enables this function.
  4. Save and close the file.
  5. Restart the Trend Micro IMSS SMTP Service.

The RFC 2821 specifies the following rules for the parts of a sender email address:

  • Local part - The maximum total length of a user name or other local part is 64 characters.
  • Domain - The maximum total length of a domain name or number is 255 characters.
  • Path - The maximum total length of a reverse-path or forward-path is 256 characters, including the punctuation and element separators.
  • Command line -The maximum total length of a command line, including the command word, is 512 characters. The SMTP extensions may be used to increase this limit.
Premium
Internal
Rating:
Category:
Troubleshoot
Solution Id:
1037107
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