Too many dovecot logins by the user dovenull

Hi, When I checked the current running processes on my mail server I found more than 100 dovecot/pop3-login by the user dovenull. Is it normal to have this? dovenull 16976 0.0 0.0 6272 2344 ? S 03:49 0:00 dovecot/pop3-login dovenull 16978 0.0 0.0 6272 2412 ? S 03:49 0:00 dovecot/pop3-login dovenull 16979 0.0 0.0 6272 2404 ? S 03:49 0:00 dovecot/pop3-login dovenull 16980 0.0 0.0 6272 2340 ? S 03:49 0:00 dovecot/pop3-login dovenull 16981 0.0 0.0 6272 2408 ? S 03:49 0:00 dovecot/pop3-login dovenull 16982 0.0 0.0 6272 2352 ? S 03:49 0:00 dovecot/pop3-login dovenull 16983 0.0 0.0 6272 2408 ? S 03:49 0:00 dovecot/pop3-login dovenull 16984 0.0 0.0 6272 2340 ? S 03:49 0:00 dovecot/pop3-login dovenull 16985 0.0 0.0 6272 2408 ? S 03:49 0:00 dovecot/pop3-login dovenull 16986 0.0 0.0 6272 2408 ? S 03:49 0:00 dovecot/pop3-login dovenull 16987 0.0 0.0 6272 2340 ? S 03:49 0:00 dovecot/pop3-login ............. We have only 10+ email clients. Can I kill those processes?