No Return Address
My biggest pet peeve would have to be -
No return address on envelopes (submissions, short story competition entries, enquiries, etc…).
Why would you trust Australia Post to ‘always’ delivery your material? I don’t think I’ve ever sent something through the post without including a way for the item to be returned to me if it could not be delivered.
When an author/writer is incapable of adding their return address to an envelope - I tend to wonder about what else they may have failed to do - and that’s before I even open their envelope. Food for thought!