I found the problem. "mail_plugins = fts fts_solr" has to be set within "protocol imap" as well.

On 2016-02-28 23:59, ralph.jones@modolingo.de wrote:

I traced the network communication with the solr server with tcpdump: sudo tcpdump -i any -A -vvv port 8080

I logged into the imap server via telnet (actually openssl) and issued the command ". search body <string>". About 20 results were returned within about half a second. Nothing was seen in tcpdump. When I issue "doveadm search box <string>", I can see the search string in the output of tcpdump and also in the solr logs. Solr seems to have been initialized correctly, in that when I issue a query via curl, I receive the correct results.

I am using: dovecot 2.2.13 (debian jessie) libsolr-java 3.6.2+dfsg-5

relevant config: mail_plugins = fts fts_solr acl virtual plugin { fts = solr fts_solr = url=http://localhost:8080/solr/ debug ... }