go build smtp.go 

 --host HOST SMTP Host (a.g. 127.0.0.1) --port PORT SMTP port [default: 10025] --noauth disable SMTP authentication --plainauth enable SMTP PLAIN authentication --anonauth enable SMTP anonymous authentication --user USER SMTP username --password PASSWORD SMTP password --region REGION AWS region (a.g. eu-west-1) --sourcearn ARN AWS Source ARN --fromarn ARN AWS From ARN --returnpatharn ARN AWS Return Path ARN --accesskey ACCESSKEY AWS Access Key --secretkey SECRETKEY AWS Secret Key --help, -h display this help and exit