AWS_ACCESS_KEY // an AWS SES access key
AWS_SECRET_KEY // an AWS SES secret key
AWS_DEFAULT_REGION // an AWS SES region, e.g.: eu-central-1
BUCKET_NAME // name of bucket with attachment files
EMAIL // default sender email address
AWS_EMAIL_RATE // number of emails per second to send, default 10
CORS_ORIGIN // allowed request origin (pattern), default: http://localhost:3000
MAX_ERRORS // number of errors till processing is suppressed, default: 3
MONGO_HOST // MongoDB host, default: localhost
MONGO_PORT // MongoDB port, default: 27017
MONGO_DB // MongoDB database name, default: subscription
MONGO_USER // MongoDB user name, default: user
MONGO_PASS // MongoDB user password, default: pass