[Dovecot] auth_username_chars - special chars

Hello,

i use dovecot 1.2.11 with auth by mysql.

auth_username_chars = abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@üÜöÖäÄ

for some reasons more special chars in username are needed. in fact the % char is meant. Is this recommend to use with mysql? should i expect some problems when using chars with special function within mysql?

Config is now:

auth default { mechanisms = plain login

passdb sql { args = /etc/dovecot/dovecot-sql.conf }

userdb prefetch { } }

password_query = SELECT inbox as user, password, home as userdb_home, uid AS userdb_uid, gid AS userdb_gid FROM mail_users WHERE login = '%u' AND active='Y'

Thanks for your ideas, Hajo