Trouble with Mailgun: Invalid 'to' address in email loop

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1

I’m having a weird issue with Mailgun. I’m trying to send a bunch of emails in a loop. The first one goes through fine, but the rest fail. They all get a 400 error saying the ‘to’ address isn’t valid. I’ve checked everything and it looks okay to me. Here’s a simplified version of what I’m doing:

def send_welcome_series(recipient, name):
    for i in range(4):
        subject = ['Hey there!', 'Check this out', 'Got questions?', 'Why not?'][i]
        response = send_email(
            to=f'{name} <{recipient}>',
            subject=subject,
            body=load_template(f'welcome_{i+1}.html'),
            send_time=calculate_send_time(i)
        )
        print(f'Email {i+1} status: {response.status_code}')
        print(f'Response: {response.json()}')

Any ideas what could be going wrong? I’m stumped!

2

hEy, i had similar trouble. try adding a short delay between emails, like 1-2 seconds. mailgun can be finicky with rapid sends. also, double check ur recipient format. sometimes extra spaces or weird characters mess it up. good luck!

3

I’ve encountered this issue before with Mailgun. The problem might be related to how you’re formatting the ‘to’ field. Try separating the name and email address like this: to=f'{name} <{recipient}>'. This format is more consistently recognized by email systems.

Also, consider implementing error handling by catching the 400 errors and logging the specific recipient that failed. This may help identify if the issue is isolated or affecting all recipients.

Lastly, ensure your Mailgun account is properly configured for bulk sending. Some additional verification steps or settings may be necessary when sending multiple emails in quick succession. If the problem persists, contacting Mailgun support might provide further insights.

4

I ran into a similar issue with Mailgun a while back. It turned out the problem was rate limiting. Even though the ‘to’ address looked valid, Mailgun was rejecting subsequent emails to the same recipient too quickly.

Try adding a delay between each email send, like time.sleep(5) after each loop iteration. This gives Mailgun’s systems a breather.

Also, double-check your API credentials and domain settings in Mailgun. Sometimes these can cause unexpected errors that masquerade as other issues.

If those don’t work, you might want to implement some error handling and retry logic. Catch the 400 errors and retry the send after a short delay. This can help overcome temporary hiccups in the API.

Lastly, consider batching your emails instead of sending them in rapid succession. This can help avoid rate limits and improve overall reliability.