As I was in the mood with 4.5.2 I just moved on and finished 4.5.3 :-)
The file ZhMsg is now completely translated (what it doesn't mean it is OK, so all feedback is welcome!).
As usual, the full package with the installation script is available at http://files.whitehatmail.fr/
The most important changes are in the spell checker and the French date zimlet.
The new French spell checker skips words written in uppercase (like LAN or IP), URLs of the kind protocol://what.ever, e-mail addresses, and words containing numbers.
I tried to skip quoted e-mails (by recognizing "^> "), but Zimbra doesn' t send the new lines to the spell checker, so AFAIK there is no way to do it.
The new French Date zimlet now handles correctly "mardi prochain" (next Tuesday), and the day names by themselves (like "mardi").
After installing the French patch, remember to clear your browser's cache before logging in Zimbra.