Fatal Error on instal - config page

I installed 7.x-1.0-beta3 (and then also tried with 7.x-1.x-dev) which, as expected, required https://drupal.org/project/mailsystem
but after enabling both modules and heading to:
admin/config/system/mimemail

I get:

Fatal error: Cannot redeclare _mimemail_replace_files() (previously declared in /home/MYSITE/public_html/sites/all/modules/messaging/messaging_htmlmail/messaging_htmlmail.inc:422) in /home/MYSITE/public_html/sites/all/modules/mimemail/mimemail.inc on line 142

This happened with both 7.x-1.0-beta3 and 7.x-1.x-dev