MyBB

If you search your system mail logs and the result is on several pages there's a problem with the links in the pagination:
index.php?module=tools/mailerrors&page=*2s*ubject=xyz

The & is missing and because of that it shows all logs if you switch between the pages.

admin/modules/tools/mailerrors.php
$additional_criteria = implode("&amp;", $additional_criteria);<br />...<br />echo "&lt;br /&gt;".draw_admin_pagination($mybb->input['page'], $per_page, $total_rows, "index.php?module=tools/mailerrors&amp;page={page}{$additional_criteria}");