According to their response they are IN TIME.
'We have considered your representations dated 14 March..'
Yes, thanks, I'm aware. But what they've said is simply not true and I can prove otherwise.
IMO, at this stage let's not get bogged down in email dates (and whether the authority have complied with the Secretary of State's Statutory Guidance) until we've exhausted the issue of letters and posting.
Well, I feel like I need to cover all bases if I'm going to write an appeal to the tribunal. Which was why my question was if I send that proof of postage and a copy of the formal appeal to the tribunal then is that definitely "game, set and match" in my favour?
Also, something else I realised. They emailed me their response and attached the Notice of Rejection. So if they can do that and expect it to be deemed served but expect that in the case of me doing the same to them it isn't deemed served they are having a laugh surely. Although this is somewhat irrespective of course seeing as proof of postage should prove it in my favour anyway.