nostr:npub1pkx92m60skq9pzs90m3yqq9tvwh03xhzc0haeqqc4exjcu7l6ntsanxwks , in case you were wondering, the recipient and subject line are not encrypted. Therefore nostr:npub1mea2vwcu06qf7e4x00wd902vj54qnn2jacq76ldntrgfhtvhlpqqrvqane can see it.

Not sure who you are sending emails to and what are the subject lines but it can be seen.

https://proton.me/blog/protonmail-threat-model