In canisters, can I call the mailbox server to send mail？Can canisters communicate with Amazon cloud platforms?
No, wasm does not support network connection.
You may see that GitHub - hyplabs/dfinity-oracle-framework
And for dfinity samples: GitHub - dfinity/awesome-dfinity: A curated list of awesome projects and resources relating to DFI
I made a proposal that would enable this: Megathread: Community Submissions for DFINITY Foundation’s Roadmap - #77 by paulyoung