I have no known terminal illness and am 18 years shy of 50..
Well, are you trustworthy?
Well the whole point is that you have to try to apply your own discernment.
A scammer won't admit to being a scammer, so if I reply "yes, I'm trustworthy", it is meaningless, and is encouraging people to not apply critical thinking.
You can try reading my posts, and ask yourself if a scammer would go to such lengths.
There are no guarantees.
Some scammers can be very clever and sophisticated, so some risk will always remain.
You can try asking around to get opinions from others.
If several well-established people vouch for me, then that can help to build some confidence.
As mentioned above :
You could also find some threads where people have ordered from A, and cross check the email addresses with some of those people.
If all of those check out, and lead to the same answer, then you can probably take a degree of confidence from that....
I think that's about as much as I can say really.....
I realise this answer must feel highly unsatisfactory, but anything else is insulting the intelligence of anyone reading, so it is what it is....