i solve the problem. the solution is set --syncinternaldates to imapsync and all goes well.

Thank you very much Timo for your answer workino

On Tue, May 13, 2008 at 7:40 PM, Timo Sirainen <tss@iki.fi> wrote:

On May 13, 2008, at 6:17 PM, Gabriele Fergola wrote:

I tried to migrate from a server courier to dovecot with imapsync but i

...

get this errore:

Couldn't append msg #15 (Subject:[Registrazione]) to folder INBOX: Error sending command '16 APPEND INBOX (\Answered \Seen) "" {3478} ': 16 BAD Invalid internal date.

It sends "" as the message's date, which clearly is broken. A "default" date could have been given by just not sending the "" at all. I'd say go complain to imapsync people.