How to delete all trash at one time on iPhone 4S

If you mean Trash from within the e-mail program, go to the main part of your e-mail account (hit the button on the upper left until there is no more button to hit.

Then, go to the e-mail account for which you wish to delete all trash (it will be under the "Accounts" line. After selecting hour account, navigate to the Trash folder.

Once there, press the Edit button (top right). You sill then see a red Delete All button appear in the lower left of the screen. Press that and your Trash will then be emptied.

Hope this helps.

Marilyn

P.S. Oh, and for more answers for an iPhone, may I suggest you visit our sister forum: www.iphoneforums.net. Here there be iPads! They have a lot more phone experts over there...