The email contains card last digits, card type, merchant name, and transaction amount.
I expect the emails themselves are just formatted strings. You could use an email parser to get the structure back out. You or someone else mentioned Zapier webhooks, so https://parser.zapier.com/ might be extra relevant.
Ah, haven't heard of parser.zapier.com before. Yes I mentioned Zapier! This could be perfect, will report back.
If Zapier Parser doesn't do the job for some reason, hit us up @ https://parseur.com (co-founder here)