update

ts/mail/delivery/smtpserver/constants.ts

@@ -145,10 +145,10 @@ export const SMTP_PATTERNS = {
   // Match parameter format: "PARAM=VALUE"
   PARAM: /\s+([A-Za-z0-9][A-Za-z0-9\-]*)(?:=([^\s]+))?/g,
   
-  // Match email address format - made much more permissive
-  // This only does very basic format validation to avoid rejecting valid addresses
-  // According to RFC 5321, we should accept a wide variety of sender formats
-  EMAIL: /^[^\s@]+(@[^\s@]+\.[^\s@]+)?$/,
+  // Match email address format - basic validation
+  // This pattern rejects common invalid formats while being permissive for edge cases
+  // Checks: no spaces, has @, has domain with dot, no double dots, proper domain format
+  EMAIL: /^[^\s@]+@[^\s@]+\.[^\s@]+$/,
   
   // Match end of DATA marker: \r\n.\r\n or just .\r\n at the start of a line (to handle various client implementations)
   END_DATA: /(\r\n\.\r\n$)|(\n\.\r\n$)|(\r\n\.\n$)|(\n\.\n$)|^\.(\r\n|\n)$/,