As a follow-up to #25755, the MimeUtility.encodeText(attachmentFilename) call should be skipped by default through setting the newly introduced encodeFilenames property to false by default in the 5.3 line (while it remains at true in 5.2.9).
As a follow-up to #25755, the MimeUtility.encodeText(attachmentFilename) call should be skipped by default through setting the newly introduced encodeFilenames property to false by default in the 5.3 line (while it remains at true in 5.2.9).