Add delay when queuing multiple debt email

[beesaferoot]

Closes #1299

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[dmohns]

Hey @beesaferoot

Two comments here

1. How do you know the error is rate limit related? I'm reading the Gmail SMTP relay docs It looks like we should be really far from any limit
   

   Also, I would have expected a rate limit error: https://support.google.com/a/answer/6140680?sjid=6095609842808687166-EU Did we see any of these?

2. Regarding the actual implementation. Can't we just use a queue-based Rate Limit? https://laravel.com/docs/12.x/queues#rate-limiting instead of a custom delay implementation? We could even go further and at exponential backoff retries on queue level.

[beesaferoot]

1. How do you know the error is rate limit related? I'm reading the Gmail SMTP relay docs It looks like we should be really far from any limit

This link (https://support.google.com/a/answer/3221692) was part of the error message, I did a little search on the cause of issues like this. I came across this (https://forum.mautic.org/t/error-sending-emails/25498/2), also asked ChatGPT.

I know our IP isn't banned entirely because we still successfully send out emails in other cases (i.e., welcome email etc), but there appears to always be an error when trying to send out debt emails. What do you suggest? without making uninformed guess, I'm not sure what to make of it yet.

Regarding the actual implementation. Can't we just use a queue-based Rate Limit? https://laravel.com/docs/12.x/queues#rate-limiting instead of a custom delay implementation? We could even go further and at exponential backoff retries on queue level.

This is a better solution. I will look into it. Thank you

[dmohns]

1. How do you know the error is rate limit related? I'm reading the Gmail SMTP relay docs It looks like we should be really far from any limit

This link (https://support.google.com/a/answer/3221692) was part of the error message, I did a little search on the cause of issues like this. I came across this (https://forum.mautic.org/t/error-sending-emails/25498/2), also asked ChatGPT.

I know our IP isn't banned entirely because we still successfully send out emails in other cases (i.e., welcome email etc), but there appears to always be an error when trying to send out debt emails. What do you suggest? without making uninformed guess, I'm not sure what to make of it yet.

Yeah, this is really tricky to understand. I'm just curious because they provide such a detailed list of SMTP Error codes: https://support.google.com/a/answer/3726730?sjid=16209648178720520903-EU

For example

550 5.7.1 This email has been rate limited.

Interestingly, the error already gives us some indication. Try again later, 😂 Are we retrying email sending?

Regarding the actual implementation. Can't we just use a queue-based Rate Limit? https://laravel.com/docs/12.x/queues#rate-limiting instead of a custom delay implementation? We could even go further and at exponential backoff retries on queue level.

This is a better solution. I will look into it. Thank you

👍

[beesaferoot]

Interestingly, the error already gives us some indication. Try again later, 😂 Are we retrying email sending?

Yes but it doesn't have any backoff logic; it simply retries immediately

[dmohns]

releaseAfter(3) seems wrong here 🤔 Below we are using releaseAfter(5 * 60). Should they be different or should they be the same?

[beesaferoot]

5 minutes is for Throttle middleware which happens only after exceeding maximum attempts. 3 seconds is meant for a delay on each attempt.

[dmohns]

Essentially, my question is, why are the values different between HtmlEmail.php and PlainEmail.php? I would have expected them to be the same.

[beesaferoot]

You are correct, that's not expected.

[beesaferoot]

Now updated.