Created attachment 2199 [details] Proposed patch. Similar to how email contents are decoded with superset encodings by default (e.g., GB18030 is used as the fallback for GB2312), this patch allows message headers to be decoded similarly. In particular, as mentioned in Bug 2110, it is common for Chinese emails to specify GB2312 but include characters in GB18030. This patch allows message subjects to be displayed correctly in those cases.