How to allow EAI - our solution

The SMTPUTF8 Extension (rfc6531 3.2)

Condition:

If SMTPUTF8 is not supported by receiving SMTP server – it Must Not transmit.  

Recommendation:

• Transform the Message
• Reject the Message
• Re queue later or try an alternate MX

Transform the Message

• Transformation are outside the scope of the RFC. Thus we Apply a Filter on the MTA (same way as SpamAssassin/ClamAv works) before sending the mail to the outgoing/final queue.
• Filter messages before sending
• Test the Recipient if it supports SMTPUTF8 extension
• Rewrite the User and Domain based on Mapping System/Mail Alias
• Send the message normally