mailWipe() will always delete.

[Hobadee]

I haven't tested this, so something may be slipping by me here, but...
In line 222:
if ( ($_ENV['wipe']) && (imap_delete($this->_c,$i)) ) return imap_expunge($this->_c);

The if() statement will run imap_delete() as part of it's evaluation, resulting in the item being marked for deletion regardless of $_ENV['wipe']. The statement should be:
if ($_ENV['wipe']) {
imap_delete($this->_c,$i);
return imap_expunge($this->_c);
}

If imap_expunge() is dependent on imap_delete() completing successfully, there should be a separate evaluation.