[Python] Django send_mail() / EmailMessage with Gmail SMTP has 4-minute delay for new email...

I’m facing a consistent email delivery delay when using Django’s built-in send_mail() or EmailMessage functions with Gmail SMTP.

Setup:

• Backend: Django (tested with both send_mail() and EmailMessage)
• SMTP: smtp.gmail.com with App Passwords
• Recipients: New or first-time email addresses (e.g., new Gmail or company emails)
• Sender: Personal Gmail account using App Password (not Google Workspace)
• Observation:
  • Emails show up instantly in the sender's Sent folder.
  • Recipient receives the email after ~4 minutes delay, only on the first send.
  • On re-sending to the same recipient, delivery is almost instant.

This is especially problematic for: Sign-up confirmation, OTP delivery, Real-time alerts or notifications

❌ What I’ve Tried:

• Tested both old and new Gmail accounts.
• Created new and old App Passwords.
• Sent using both send_mail() and EmailMessage.
• Tried different recipient domains (Gmail, Outlook, work domains, etc.).
• Verified there’s no error or SMTP failure — just delay.

Additional Notes:

• The issue does not occur for known recipients.
• SMTP works fine; it's the delivery to new recipients that lags.
• Server is configured correctly, no IPv6 hangups.
• Delay seems similar to what Gmail does with anti-phishing checks, but I'm unsure if there’s a Django-specific fix or workaround.

❓ Question:

• 
  Is this behavior normal when using Gmail SMTP via Django?
  
  
• 
  Is there a known workaround to eliminate or reduce this delay for new recipients?
  
  
• 
  Would using OAuth or switching to a transactional email provider (SendGrid, Mailgun, etc.) help eliminate this delay?
  

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