Roundcubemail problem with Dovecot

[Robert Moskowitz]

I am getting "Connection to storage server failed." in roundcubemail.  
On doing a google search If find:

http://help.directadmin.com/item.php?id=473

Which puts the problem at dovecot.  I did get a dovecot update back on 
3-5 and that would match to my one roundcube mail user complaining and 
the delays I am seeing with thunderbird and outlook users.

So with my setup, I am trying to figure what are the index files to 
delete.  Say for myself, I am seeing:

/home/vmail/htt-consult.com/rgm/dovecot.index
/home/vmail/htt-consult.com/rgm/dovecot.index.cache
/home/vmail/htt-consult.com/rgm/dovecot.index.log
/home/vmail/htt-consult.com/rgm/.Drafts/dovecot.index
/home/vmail/htt-consult.com/rgm/.Drafts/dovecot.index.cache
/home/vmail/htt-consult.com/rgm/.Drafts/dovecot.index.log
/home/vmail/htt-consult.com/rgm/.Sent/dovecot.index
/home/vmail/htt-consult.com/rgm/.Sent/dovecot.index.cache
/home/vmail/htt-consult.com/rgm/.Sent/dovecot.index.log
/home/vmail/htt-consult.com/rgm/.Spam/dovecot.index
/home/vmail/htt-consult.com/rgm/.Spam/dovecot.index.cache
/home/vmail/htt-consult.com/rgm/.Spam/dovecot.index.log
/home/vmail/htt-consult.com/rgm/.Trash/dovecot.index
/home/vmail/htt-consult.com/rgm/.Trash/dovecot.index.cache
/home/vmail/htt-consult.com/rgm/.Trash/dovecot.index.log

Do I delete all of these?  The index.cache files are quite large.