fix: outgoing email account handlng (backport #24656) (#24657)

* fix: Bail if no SMTP acccount can be found

Currently we give this weird error instead of just saying no outgoing email account is configured.

```
AttributeError: 'NoneType' object has no attribute 'get_smtp_server'
  File "frappe/email/queue.py", line 154, in flush
    email_queue.send()
  File "frappe/email/doctype/email_queue/email_queue.py", line 160, in send
    with SendMailContext(self, smtp_server_instance) as ctx:
  File "frappe/email/doctype/email_queue/email_queue.py", line 236, in __init__
    self.smtp_server: SMTPServer = smtp_server_instance or self.email_account_doc.get_smtp_server()
```

(cherry picked from commit 78665d9)

* fix: Fetch SMTP server inside context

Currently if smtp server creation fails email queue is endlessly
retried. It should just fail if there's no outgoing account.

(cherry picked from commit dae99eb)

---------

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

frappe/email/doctype/email_queue/email_queue.py

@@ -131,12 +131,12 @@ def to(self):
 	def attachments_list(self):
 		return json.loads(self.attachments) if self.attachments else []
 
-	def get_email_account(self):
+	def get_email_account(self, raise_error=False):
 		if self.email_account:
 			return frappe.get_cached_doc("Email Account", self.email_account)
 
 		return EmailAccount.find_outgoing(
-			match_by_email=self.sender, match_by_doctype=self.reference_doctype
+			match_by_email=self.sender, match_by_doctype=self.reference_doctype, _raise_error=raise_error
 		)
 
 	def is_to_be_sent(self):
@@ -158,6 +158,7 @@ def send(self, smtp_server_instance: SMTPServer = None):
 			return
 
 		with SendMailContext(self, smtp_server_instance) as ctx:
+			ctx.fetch_smtp_server()
 			message = None
 			for recipient in self.recipients:
 				if recipient.is_mail_sent():
@@ -231,14 +232,16 @@ def __init__(
 		smtp_server_instance: SMTPServer = None,
 	):
 		self.queue_doc: EmailQueue = queue_doc
-		self.email_account_doc = queue_doc.get_email_account()
-
-		self.smtp_server: SMTPServer = smtp_server_instance or self.email_account_doc.get_smtp_server()
-
+		self.smtp_server: SMTPServer = smtp_server_instance
 		self.sent_to_atleast_one_recipient = any(
 			rec.recipient for rec in self.queue_doc.recipients if rec.is_mail_sent()
 		)
 
+	def fetch_smtp_server(self):
+		self.email_account_doc = self.queue_doc.get_email_account(raise_error=True)
+		if not self.smtp_server:
+			self.smtp_server = self.email_account_doc.get_smtp_server()
+
 	def __enter__(self):
 		self.queue_doc.update_status(status="Sending", commit=True)
 		return self
@@ -730,7 +733,7 @@ def send_emails(self, queue_data, final_recipients):
 			recipients = list(set([r] + self.final_cc() + self.bcc))
 			q = EmailQueue.new({**queue_data, **{"recipients": recipients}}, ignore_permissions=True)
 			if not smtp_server_instance:
-				email_account = q.get_email_account()
+				email_account = q.get_email_account(raise_error=True)
 				smtp_server_instance = email_account.get_smtp_server()
 
 			with suppress(Exception):