/dev/characters/{character_id}/mail/{mail_id}/
/legacy/characters/{character_id}/mail/{mail_id}/
/v1/characters/{character_id}/mail/{mail_id}/
curl --location --request PUT 'https://esi.evetech.net/latest/characters//mail//' \
--header 'Content-Type: application/json' \
--data-raw '{
"labels": [
0
],
"read": true
}'
{}