Swiftaid Reviews 

I got an unsolicited email from Swiftaid regarding Giftaid. Never heard of them, & certainly never signed up for their service. It's "red flags" all over as far as I can tell from the email, hence 1 star.
That said, their website has a valid certificate, & Justgiving states "Swiftaid is an ISO 27001 and ISO 22301 accredited company".
It's most likely a genuine 3rd party service provider to charities, but unless charity donors are clearly told to expect emails from them, the only safe action for anyone to do is send their emails to the spam bin.

I don't know who this is but got email with 2 links implying it's something to do with HMRC.
As I'm not keen on using such links, I can see no way of accessing my data assuming it's not a spam.
If it's genuine, why doesn't HMRC do their own work

I found it very troubling that this company, without my permission, links information about my charitable donations and then overrides my original requests on whether to claim gift aid - sending a note that says they will automatically apply it unless I take steps to decline again, and taking up to 10 percent of the proceeds for themselves. I don’t think the charities involved know Swiftaid’s questionable process of automatically overriding donor’s original requests. It makes me less likely to contribute at all to Gofundme or Movember (the two charities involved in sharing my information with them and then allowing them to back-claim previous donations unless I log on and tell them not to) due to Swiftaid’s relationship with them.