diff --git a/src/storage/s3.js b/src/storage/s3.js
index 06865385e..a39c66145 100644
--- a/src/storage/s3.js
+++ b/src/storage/s3.js
@@ -416,6 +416,11 @@ function testConfig(apiConfig, callback) {
     // the node module seems to incorrectly accept bucket name with '/'
     if (apiConfig.bucket.includes('/')) return callback(new BoxError(BoxError.BAD_FIELD, 'bucket name cannot contain "/"', { field: 'bucket' }));
 
+    // names must be lowercase and start with a letter or number. can contain dashes
+    if (apiConfig.bucket.includes('_') || apiConfig.bucket.match(/[A-Z]/)) return callback(new BoxError(BoxError.BAD_FIELD, 'bucket name cannot contain "_" or capitals', { field: 'bucket' }));
+
+    if (apiConfig.bucket.includes('.')) return callback(new BoxError(BoxError.BAD_FIELD, 'Use of bucket names with "." is discouraged. Use the "S3 API Compatible" provider and accept self-signed certificate if you really need this', { field: 'bucket' }));
+
     if (typeof apiConfig.prefix !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'prefix must be a string', { field: 'prefix' }));
     if ('signatureVersion' in apiConfig && typeof apiConfig.signatureVersion !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'signatureVersion must be a string', { field: 'signatureVersion' }));
     if ('endpoint' in apiConfig && typeof apiConfig.endpoint !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'endpoint must be a string', { field: 'endpoint' }));