fix: preserve original error message (#25682) (#25684)

(cherry picked from commit 85f66c0)

Co-authored-by: Ankush Menat <ankush@frappe.io>

frappe/email/smtp.py

@@ -7,7 +7,7 @@
 import frappe
 from frappe import _
 from frappe.email.oauth import Oauth
-from frappe.utils import cint, cstr
+from frappe.utils import cint, cstr, get_traceback
 
 
 class InvalidEmailCredentials(frappe.ValidationError):
@@ -115,8 +115,9 @@ def quit(self):
 
 	@classmethod
 	def throw_invalid_credentials_exception(cls):
+		original_exception = get_traceback() or "\n"
 		frappe.throw(
-			_("Please check your email login credentials."),
+			_("Please check your email login credentials.") + " " + original_exception.splitlines()[-1],
 			title=_("Invalid Credentials"),
 			exc=InvalidEmailCredentials,
 		)