Format |
public bool AllowMixedHeaderCharsets { get; set; }
When this option is enabled, the MIME formatter will try to use us-ascii and/or iso-8859-1 to encode headers when appropriate rather than being forced to use the specified charset for all encoded-word tokens in order to maximize readability.
Unfortunately, mail clients like Outlook and Thunderbird do not treat encoded-word tokens individually and assume that all tokens are encoded using the charset declared in the first encoded-word token despite the specification explicitly stating that each encoded-word token should be treated independently.
The Thunderbird bug can be tracked at https://bugzilla.mozilla.org/show_bug.cgi?id=317263.