Thank you! I really don't know what I made, but now all works fine with Thunderbird and Outlook 2007.

But something strange: 'uidvalidity' are the same for both servers, but UIDs of mesages are not:

Courier: d fetch 1:* uid

• 1 FETCH (UID 64295)
• 2 FETCH (UID 64296)
• 3 FETCH (UID 64297)

Dovecot:

• 1 FETCH (UID 64296)
• 2 FETCH (UID 64297)
• 3 FETCH (UID 64298)

There can be it because of that that the server is used?

04.04.2012, 06:57, "Timo Sirainen" <tss@iki.fi>:

On 3.4.2012, at 15.33, xnasx wrote:

...

 I trying to migrate to Dovecot 2.0.18 from Courier 4.10. I using a script 'courier-dovecot-migrate.pl' from oficial wiki - it works without errors and creating dovecot-uidlist, etc. .

 I running Dovecot on a different port: 11149. When I connecting to port 11149 from Thunderbird, all my message headers are reloading.

 Please help me to solve this issue.

telnet localhost 143 a login user pass b select inbox c status inbox (uidvalidity) d fetch 1:* uid

telnet localhost 11149 a login user pass b select inbox c status inbox (uidvalidity) d fetch 1:* uid

Check if the "c" and "d" outputs are the same for both servers. If they are, then the migration was successful and the problem is something else, such as maybe the client always redownloading messages because you changed the port (or something else).