SMTP Server Login Error An error occurred : character mapping must return integer, None or unicode

I am using Power Email 5.0.0.7 RC with python2.6 in openERP Sever 5.0.10
When I try to check outgoing Connection, this error is showed:
"SMTP Server Login Error An error occurred : character mapping must return integer, None or unicode "

stack trace :

[2010-05-18 09:31:16,240] DEBUG:Connection:create cursor to "laboratoriosPruebas"
[2010-05-18 09:31:16,240] DEBUG:ConnectionPool:ConnectionPool(used=0/count=1/max=64) Borrow connection to user=leo dbname=laboratoriosPruebas
[2010-05-18 09:31:16,240] DEBUG:ConnectionPool:ConnectionPool(used=1/count=1/max=64) Existing connection found at index 0
[2010-05-18 09:31:16,427] DEBUG:ConnectionPool:ConnectionPool(used=1/count=1/max=64) Give back connection to user=leo dbname=laboratoriosPruebas
[2010-05-18 09:31:16,428] DEBUG:ConnectionPool:ConnectionPool(used=0/count=1/max=64) Put connection to user=leo dbname=laboratoriosPruebas in pool
/usr/lib/python2.5/site-packages/openerp-server/tools/misc.py:750: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6
  if hasattr(e, 'message'):
/usr/lib/python2.5/site-packages/openerp-server/tools/misc.py:751: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6
  return ustr(e.message)
[2010-05-18 09:31:16,429] DEBUG_RPC:exception:u'warning -- SMTP Server Login Error\n\nAn error occurred : character mapping must return integer, None or unicode '
[2010-05-18 09:31:16,738] DEBUG_RPC:service:'object'
[2010-05-18 09:31:16,738] DEBUG_RPC:method:'execute'
[2010-05-18 09:31:16,740] DEBUG_RPC:params:[01]: ('laboratoriosPruebas',
[2010-05-18 09:31:16,740] DEBUG_RPC:params:[02]: 1,
[2010-05-18 09:31:16,740] DEBUG_RPC:params:[04]: 'ir.attachment',
[2010-05-18 09:31:16,740] DEBUG_RPC:params:[05]: 'search_count',
[2010-05-18 09:31:16,741] DEBUG_RPC:params:[06]: [('res_model', '=', u'poweremail.core_accounts'), ('res_id', '=', 1)])
[2010-05-18 09:31:16,741] DEBUG:Connection:create cursor to "laboratoriosPruebas"

Not always, I tried with two email accounts with one work and the other is not

It's a problem with python2.6.

I fixed writing in poweremail_core.py :

def out_connection(self, cr, uid, ids, context={}):
...........
                try:
                    if serv.has_extn('AUTH') or rec.smtpuname or rec.smtppass:
                        serv.login(rec.smtpuname.encode('utf-8'), rec.smtppass.encode('utf-8'))
..............