BUG? Sieve function redirect :copy "...", original rcpt gets original msg not changed msg (addheader/deleteheader)

[T-Doschke]

when a sieve script does
...
addheader "x-..." "value"
...
if condition {
redirect :copy "address"
}

then the mail where delivered to original rcpt and a copy goes to the redirect address.
But only the :copy Mail has this header.
the original rcpt gets the mail without header.

change sieve script to not include the redirect :copy command, then the header is seen in delivered mail.
So its seems that the redir :copy copyied internal the actual msg for the redirect address but that destroyes all changes like addheader or deleteheader for the original rcpt.

think this is a bug and not intended.

[T-Doschke]

have found what i have done wrong.
a redirect :copy has an implicit keep.
but that implicit keep, keeps only the original msg, not the manipulated msg the sieve script is
working on (without addheader/deleteheader).
So

redirect :copy "addresse"; keep;

is the solution.
This explicit keep command will keep the manipulated msg for delivery.