{"id":2736,"date":"2025-05-13T16:32:41","date_gmt":"2025-05-13T16:32:41","guid":{"rendered":"https:\/\/pheonixsolutions.com\/knowledge-base\/?p=2736"},"modified":"2025-05-13T16:32:45","modified_gmt":"2025-05-13T16:32:45","slug":"how-to-enable-smtputf8-with-exim","status":"publish","type":"post","link":"https:\/\/pheonixsolutions.com\/knowledge-base\/2025\/05\/13\/how-to-enable-smtputf8-with-exim\/","title":{"rendered":"How to enable SMTPUTF8 with Exim"},"content":{"rendered":"\n

Introduction:<\/strong>
In today\u2019s globalized digital landscape, email systems must be capable of handling internationalized content\u2014including addresses with non-ASCII characters. This is where SMTPUTF8<\/strong> comes into play.<\/p>\n\n\n\n

SMTPUTF8<\/strong> is an SMTP extension defined in RFC 6531<\/a> that allows email addresses and headers to contain UTF-8 encoded characters. This enables the use of accented letters, non-Latin scripts, and other Unicode characters, making email more accessible and inclusive across different languages and regions.

If our clients are attempting to use SMTPUTF8 while your server does not have it enabled, you may encounter errors similar to the following in the \/var\/log\/exim_mainlog<\/code>:<\/p>\n\n\n\n

2025-12-15 15:26:00.383 [3539516] SMTP syntax error in \"MAIL FROM: <test@example.tld> SMTPUTF8\n\n\" H=(hostname) [xxx.xxx.xxx.xxx]:55653 I=[xxx.xxx.xxx.xxx]:465 SMTPUTF8 used when not advertised\n<\/code><\/pre>\n\n\n\n
This error occurs because the client requests SMTPUTF8 support that the server has not advertised, causing the server to reject the message.<\/p>\n\n\n\n
To resolve this issue and ensure smooth communication with modern mail clients, you need to enable specific settings in Exim to support SMTPUTF8. The procedure below outlines how to do this through WHM (Web Host Manager)<\/strong>.<\/p>\n\n\n\n
Procedure to Enable SMTPUTF8 in Exim<\/strong><\/p>\n\n\n\n
    \n
  1. Log in to WHM as the root user<\/strong>\n