I encounter a strange error. The email sending stopped working since yesterday before all was fine. I did not change a thing at all.

Error message is:

  2024-07-11 09:35:01,147 share.email.service ERROR    Traceback (most recent call last):
  File "/srv/deduu/./share/email/service.py", line 318, in send_email_from_template
    cls.send_admin_email(subject, recipient_list, html_message=message)
  File "/srv/deduu/./share/email/service.py", line 330, in send_admin_email
    cls.send_email(subject, from_mail, recipient_list, message, html_message)
  File "/srv/deduu/./share/email/service.py", line 279, in send_email
    return email_wrapper.send_mail()
  File "/srv/deduu/./share/email/service.py", line 91, in send_mail
    return_value = bool(self.mail.send())
  File "/srv/deduu/.venv/lib/python3.8/site-packages/django/core/mail/message.py", line 284, in send
    return self.get_connection(fail_silently).send_messages([self])
  File "/srv/deduu/.venv/lib/python3.8/site-packages/django/core/mail/backends/smtp.py", line 109, in send_messages
    sent = self._send(message)
  File "/srv/deduu/.venv/lib/python3.8/site-packages/django/core/mail/backends/smtp.py", line 125, in _send
    self.connection.sendmail(from_email, recipients, message.as_bytes(linesep='rn'))
  File "/usr/lib/python3.8/smtplib.py", line 874, in sendmail
    (code, resp) = self.mail(from_addr, esmtp_opts)
  File "/usr/lib/python3.8/smtplib.py", line 539, in mail
    return self.getreply()
  File "/usr/lib/python3.8/smtplib.py", line 398, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")
smtplib.SMTPServerDisconnected: Connection unexpectedly closed 

Strangely the sending of the mail works with a testscript with the same credentials and settings but using this snippet

from email.message import EmailMessage
import smtplib

username = "[email protected]"
password = r"*****"
smtp_server = "mail.test.de"
smtp_port = 47999
receiver_email = "[email protected]"

subject = 'Test Email'
body = 'This is a test email sent using smtplib in Python.'

# Create message
em = EmailMessage()
em['From'] = username
em['To'] = receiver_email
em['Subject'] = subject
em.set_content(body)

try:
    # Connect to the SMTP server
    with smtplib.SMTP(smtp_server, smtp_port) as smtp:
        smtp.starttls()
        smtp.set_debuglevel(1)
        smtp.login(username, password)
        smtp.sendmail(username, receiver_email, em.as_string())
        smtp.quit()
except Exception as e:
        print(f"Unexpected error: {e}")

Email is used as follow (excerpt):

email_connection = get_connection()   
email_connection.host = "mail.test.de"
email_connection.port = 47999
email_connection.username = [email protected]
email_connection.password = r"*****"
email_connection.use_tls = True    
      
mail = EmailMultiAlternatives(subject, message, from_email, recipient_list)
    
mail.connection = email_connection
    
if html_message:
    mail.attach_alternative(html_message, "text/html")
        
mail.send()

Anyone has an idea?