diff --git a/frappe/desk/doctype/notification_log/notification_log.py b/frappe/desk/doctype/notification_log/notification_log.py
index e6e13dafe7..c585a81826 100644
--- a/frappe/desk/doctype/notification_log/notification_log.py
+++ b/frappe/desk/doctype/notification_log/notification_log.py
@@ -29,6 +29,7 @@ class NotificationLog(Document):
 		read: DF.Check
 		subject: DF.Text | None
 		type: DF.Literal["Mention", "Energy Point", "Assignment", "Share", "Alert"]
+
 	# end: auto-generated types
 	def after_insert(self):
 		frappe.publish_realtime("notification", after_commit=True, user=self.for_user)
@@ -115,18 +116,17 @@ def _get_user_ids(user_emails):
 	return [user for user in user_names if is_notifications_enabled(user)]
 
 
-def send_notification_email(doc):
-
+def send_notification_email(doc: NotificationLog):
 	if doc.type == "Energy Point" and doc.email_content is None:
 		return
 
 	from frappe.utils import get_url_to_form, strip_html
 
-	email = frappe.db.get_value("User", doc.for_user, "email")
-	if not email:
+	user = frappe.db.get_value("User", doc.for_user, fieldname=["email", "language"], as_dict=True)
+	if not user:
 		return
 
-	header = get_email_header(doc)
+	header = get_email_header(doc, user.language)
 	email_subject = strip_html(doc.subject)
 	args = {
 		"body_content": doc.subject,
@@ -140,7 +140,7 @@ def send_notification_email(doc):
 		args["doc_link"] = get_url_to_form(doc.document_type, doc.document_name)
 
 	frappe.sendmail(
-		recipients=email,
+		recipients=user.email,
 		subject=email_subject,
 		template="new_notification",
 		args=args,
@@ -149,14 +149,14 @@ def send_notification_email(doc):
 	)
 
 
-def get_email_header(doc):
+def get_email_header(doc, language: str | None = None):
 	docname = doc.document_name
 	header_map = {
-		"Default": _("New Notification"),
-		"Mention": _("New Mention on {0}").format(docname),
-		"Assignment": _("Assignment Update on {0}").format(docname),
-		"Share": _("New Document Shared {0}").format(docname),
-		"Energy Point": _("Energy Point Update on {0}").format(docname),
+		"Default": _("New Notification", lang=language),
+		"Mention": _("New Mention on {0}", lang=language).format(docname),
+		"Assignment": _("Assignment Update on {0}", lang=language).format(docname),
+		"Share": _("New Document Shared {0}", lang=language).format(docname),
+		"Energy Point": _("Energy Point Update on {0}", lang=language).format(docname),
 	}
 
 	return header_map[doc.type or "Default"]
diff --git a/frappe/desk/form/assign_to.py b/frappe/desk/form/assign_to.py
index dc8dbc7cf5..e0de030303 100644
--- a/frappe/desk/form/assign_to.py
+++ b/frappe/desk/form/assign_to.py
@@ -253,8 +253,10 @@ def notify_assignment(
 	if not (assigned_by and allocated_to and doc_type and doc_name):
 		return
 
+	assigned_user = frappe.db.get_value("User", allocated_to, ["language", "enabled"], as_dict=True)
+
 	# return if self assigned or user disabled
-	if assigned_by == allocated_to or not frappe.db.get_value("User", allocated_to, "enabled"):
+	if assigned_by == allocated_to or not assigned_user.enabled:
 		return
 
 	# Search for email address in description -- i.e. assignee
@@ -263,14 +265,16 @@ def notify_assignment(
 	description_html = f"<div>{description}</div>" if description else None
 
 	if action == "CLOSE":
-		subject = _("Your assignment on {0} {1} has been removed by {2}").format(
-			frappe.bold(_(doc_type)), get_title_html(title), frappe.bold(user_name)
-		)
+		subject = _(
+			"Your assignment on {0} {1} has been removed by {2}", lang=assigned_user.language
+		).format(frappe.bold(_(doc_type)), get_title_html(title), frappe.bold(user_name))
 	else:
 		user_name = frappe.bold(user_name)
-		document_type = frappe.bold(_(doc_type))
+		document_type = frappe.bold(_(doc_type, lang=assigned_user.language))
 		title = get_title_html(title)
-		subject = _("{0} assigned a new task {1} {2} to you").format(user_name, document_type, title)
+		subject = _("{0} assigned a new task {1} {2} to you", lang=assigned_user.language).format(
+			user_name, document_type, title
+		)
 
 	notification_doc = {
 		"type": "Assignment",
diff --git a/frappe/email/doctype/email_queue/email_queue.py b/frappe/email/doctype/email_queue/email_queue.py
index 828ae2e419..91ca2bbdbb 100644
--- a/frappe/email/doctype/email_queue/email_queue.py
+++ b/frappe/email/doctype/email_queue/email_queue.py
@@ -6,7 +6,7 @@ import quopri
 import traceback
 from contextlib import suppress
 from email.parser import Parser
-from email.policy import SMTPUTF8, default
+from email.policy import SMTP
 
 import frappe
 from frappe import _, safe_encode, task
@@ -169,7 +169,9 @@ class EmailQueue(Document):
 				else:
 					if not frappe.flags.in_test or frappe.flags.testing_email:
 						ctx.smtp_server.session.sendmail(
-							from_addr=self.sender, to_addrs=recipient.recipient, msg=message
+							from_addr=self.sender,
+							to_addrs=recipient.recipient,
+							msg=message.decode("utf-8").encode(),
 						)
 
 				ctx.update_recipient_status_to_sent(recipient)
@@ -264,7 +266,7 @@ class SendMailContext:
 	@savepoint(catch=Exception)
 	def notify_failed_email(self):
 		# Parse the email body to extract the subject
-		subject = Parser(policy=default).parsestr(self.queue_doc.message)["Subject"]
+		subject = Parser(policy=SMTP).parsestr(self.queue_doc.message)["Subject"]
 
 		# Construct the notification
 		notification = frappe.new_doc("Notification Log")
@@ -281,7 +283,7 @@ class SendMailContext:
 		recipient.update_db(status="Sent", commit=True)
 
 	def get_message_object(self, message):
-		return Parser(policy=SMTPUTF8).parsestr(message)
+		return Parser(policy=SMTP).parsestr(message)
 
 	def message_placeholder(self, placeholder_key):
 		# sourcery skip: avoid-builtin-shadow
@@ -293,9 +295,10 @@ class SendMailContext:
 		}
 		return map.get(placeholder_key)
 
-	def build_message(self, recipient_email):
+	def build_message(self, recipient_email) -> bytes:
 		"""Build message specific to the recipient."""
 		message = self.queue_doc.message
+
 		if not message:
 			return ""
 
diff --git a/frappe/email/email_body.py b/frappe/email/email_body.py
index 449c0b5b15..80348df394 100755
--- a/frappe/email/email_body.py
+++ b/frappe/email/email_body.py
@@ -1,6 +1,5 @@
 # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
 # License: MIT. See LICENSE
-
 import email.utils
 import os
 import re
@@ -136,8 +135,8 @@ class EMail:
 		self.subject = subject
 		self.expose_recipients = expose_recipients
 
-		self.msg_root = MIMEMultipart("mixed", policy=policy.SMTPUTF8)
-		self.msg_alternative = MIMEMultipart("alternative", policy=policy.SMTPUTF8)
+		self.msg_root = MIMEMultipart("mixed", policy=policy.SMTP)
+		self.msg_alternative = MIMEMultipart("alternative", policy=policy.SMTP)
 		self.msg_root.attach(self.msg_alternative)
 		self.cc = cc or []
 		self.bcc = bcc or []
@@ -186,7 +185,7 @@ class EMail:
 		"""
 		from email.mime.text import MIMEText
 
-		part = MIMEText(message, "plain", "utf-8", policy=policy.SMTPUTF8)
+		part = MIMEText(message, "plain", "utf-8", policy=policy.SMTP)
 		self.msg_alternative.attach(part)
 
 	def set_part_html(self, message, inline_images):
@@ -199,9 +198,9 @@ class EMail:
 			message, _inline_images = replace_filename_with_cid(message)
 
 			# prepare parts
-			msg_related = MIMEMultipart("related", policy=policy.SMTPUTF8)
+			msg_related = MIMEMultipart("related", policy=policy.SMTP)
 
-			html_part = MIMEText(message, "html", "utf-8", policy=policy.SMTPUTF8)
+			html_part = MIMEText(message, "html", "utf-8", policy=policy.SMTP)
 			msg_related.attach(html_part)
 
 			for image in _inline_images:
@@ -215,7 +214,7 @@ class EMail:
 
 			self.msg_alternative.attach(msg_related)
 		else:
-			self.msg_alternative.attach(MIMEText(message, "html", "utf-8", policy=policy.SMTPUTF8))
+			self.msg_alternative.attach(MIMEText(message, "html", "utf-8", policy=policy.SMTP))
 
 	def set_html_as_text(self, html):
 		"""Set plain text from HTML"""
@@ -228,7 +227,7 @@ class EMail:
 		from email.mime.text import MIMEText
 
 		maintype, subtype = mime_type.split("/")
-		part = MIMEText(message, _subtype=subtype, policy=policy.SMTPUTF8)
+		part = MIMEText(message, _subtype=subtype, policy=policy.SMTP)
 
 		if as_attachment:
 			part.add_header("Content-Disposition", "attachment", filename=filename)
@@ -342,7 +341,7 @@ class EMail:
 		"""validate, build message and convert to string"""
 		self.validate()
 		self.make()
-		return self.msg_root.as_string(policy=policy.SMTPUTF8)
+		return self.msg_root.as_string(policy=policy.SMTP)
 
 
 def get_formatted_html(