#12 Non-ASCII display names in mail headers are not MIME encoded

[Thomas Gränicher]

Display names used in address headers are written without RFC 2047 MIME encoding.
For example, a sender name containing an umlaut:
Förderung mail@example.com
may be emitted with the UTF-8 character directly in the header.
This caused policy rejections from GMX (554 Reject due to policy restrictions). After temporarily changing the sender name from Förderung to Foerderung, these bounces stopped occurring.

Suggested fix
In EmailFormatRFC(), MIME-encode the display name only:
$rz .= self::MbEncode(self::EmailExtractName($name)) . " ";
The email address itself must remain unchanged.
With the corrected MbEncode() implementation, ASCII-only display names remain unchanged, while names containing non-ASCII characters are emitted as RFC 2047 encoded words, e.g.:
From: =?UTF-8?B?...?= <mail@example.com>
The same handling should apply to display names in From, To, Cc, and Reply-To headers.

[Andy Prevost (CodeworxTech)]

accepted as reported, fix in three separate locations (contained in Aug 10 2026 release).