Heres the section from the Manual, would be interested if you have checked this. (I dont use pop so cant confirm)


Delete mail messages
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To delete a mail message, select the message and .
For POP3 accounts, if you have activated the Leave messages
on server option in the incoming mail settings, the message
is only deleted from your device. If you deactivate the option
and want to delete the message from the server, select the
message and Delete.
For IMAP4 accounts, the messages you delete are always
deleted from the server.

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