curl --location --request POST 'https://gmail.googleapis.com//gmail/v1/users//settings/sendAs//smimeInfo' \
--header 'Content-Type: application/json' \
--data-raw '{
"encryptedKeyPassword": "string",
"expiration": "string",
"id": "string",
"isDefault": true,
"issuerCn": "string",
"pem": "string",
"pkcs12": "string"
}'
{
"encryptedKeyPassword": "string",
"expiration": "string",
"id": "string",
"isDefault": true,
"issuerCn": "string",
"pem": "string",
"pkcs12": "string"
}