There is an issue when working in the E-mails tab while editing a webform.
When you take any action that loads a new form you lose all the tabs along the top. Actions include Add, Edit and Delete.
It looks like the issue is that these items are defined as MENU_CALLBACKs rather than MENU_LOCAL_TASKs. I will submit a patch to make this change. Is there a specific reason these are not MENU_LOCAL_TASKs? Thanks.