i found the problem
you have the same problem with me and me too i change my server
just rebuild this
INSERT INTO xoops_config VALUES (64, 0, 6, 'mailmethod', '_MD_AM_MAILERMETHOD', 'mail', '_MD_AM_MAILERMETHODDESC', 'select', 'text', 4);
INSERT INTO xoops_config VALUES (65, 0, 6, 'smtphost', '_MD_AM_SMTPHOST', 'a:1:{i:0;s:0:"";}', '_MD_AM_SMTPHOSTDESC', 'textarea', 'array', 6);
INSERT INTO xoops_config VALUES (66, 0, 6, 'smtpuser', '_MD_AM_SMTPUSER', '', '_MD_AM_SMTPUSERDESC', 'textbox', 'text', 7);
INSERT INTO xoops_config VALUES (67, 0, 6, 'smtppass', '_MD_AM_SMTPPASS', '', '_MD_AM_SMTPPASSDESC', 'password', 'text', 8);
INSERT INTO xoops_config VALUES (68, 0, 6, 'sendmailpath', '_MD_AM_SENDMAILPATH', '/usr/sbin/sendmail', '_MD_AM_SENDMAILPATHDESC', 'textbox', 'text', 5);
INSERT INTO xoops_config VALUES (69, 0, 6, 'from', '_MD_AM_MAILFROM', '', '_MD_AM_MAILFROMDESC', 'textbox', 'text', 1);
INSERT INTO xoops_config VALUES (70, 0, 6, 'fromname', '_MD_AM_MAILFROMNAME', '', '_MD_AM_MAILFROMNAMEDESC', 'textbox', 'text', 2);
instead old one
now you can go to preferences and change the mail preference
but you can not send mail because there are an error in groups after change server
if you find the fix plz tell me
thanks