cannot delete emails in the mail app

Hi davidfromgrangemouth,

Thanks for contacting Apple Support Communities!

We understand that you're unable to delete email messages from your Mac. Can you tell us what happens when you try? Do you see an alert? If so, what does the message say?

In the meantime, here is a handy guide which will show you how to delete email on your Mac: Delete emails in Mail on Mac - Apple Support

Delete an email

1. In the Mail app  on your Mac, select a message.

2. Click the Delete button  in the Mail toolbar or move the pointer over the message’s header, then click the Delete button that appears.

Tip: To prevent the next message in the list from being automatically selected (and marked as read), press and hold the Option key when you delete the message.

If you set the “Move discarded messages” option to Trash in Viewing settings in Mail, you can delete a message by swiping left on the trackpad with two fingers or by moving the pointer over a Mail notification, then clicking Delete (or the Trash icon).

We look forward to your reply.

Cheers!

I have the same issue in my Sent box. They all reappear after a few seconds if I use Select All. I found however that if you select approx 5 emails at a time they will go into the trash and you can then delete. Not the best method but it's a workaround. HTH.