[imp] Non-english characters in message list

[vrasidas tsalapataras]

I have a strange issue here and I've been trying to resolve it for quite
some time now. When I am receiving e-mails with greek characters in their
sender or subject, sometimes appear as "??????" in the message list. This
does not happen for all of them though, and this is the confusing part.
Messages sent with either UTF-8, ISO-8859-7 or Windows-1253 appear
correctly. The messed up messages are all iso-8859-7 too and will not show
as characters whatever encoding i set in the browser (while other
iso-8859-7 below look fine).
Now, to make this even stranger, when I click on them to open, all the
greek characters (both in the sender/subject and the message body) appear
just fine as they should be.  So, this only happens in the message list. I
tried both on traditional and dynamic interface.
Also checked the headers, and the problematic messages are either base64 or
8-bit... Tried enabling uuencode but did not help. I am not sure if this is
relevant at all.
I am using Horde 3.3.11 with IMP 4.3.9 on PHP 5.2 . The server's operating
system is Gentoo linux.