The import and export functions ARE NOT for backup. If you want to backup you should consider to backup the prefix ?>newsletter* tables.

init(); ?>

	select('separator', array(';' => 'Semicolon', ',' => 'Comma', 'tab' => 'Tabulation')); ?> Try to change the separator if Excel does not recognize the columns.
	lists_select('list', __('All', 'newsletter')); ?>

button('export', __('Export', 'newsletter')); ?>