Greylisting and missing emails

Maintenance
1

I had a suspicion that I was missing emails but I could not put my finger on it. Below is an example of a Spotify email around the end of a free trial and the start the monthly payments. However I never received it…

I suspect because Spotify resend the email twice within minutes from a different email server so it gets rejected 3 times in total. I received Spotify emails in the past but I missed this important one.

Not sure how this can be avoided.

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2

This guide can help you set up whitelisting for postgrey.

3

Thanks whitelisting is a symptomatic solution but this does not address the root cause of the issue. I am trying to understand if:

  • either Spotify is using bad practice by resending rejected emails from different mail servers and there is simply no solution if greylisting is used
  • there are other solutions like greylisting can be setup at a different level like domain level instead of mailserver. This way if one spotify server is whitelisted they all are.

Should I just accept this or is there a way to improve without explicitly whitelisting because this is after the facts

4

Well, you can whitelist spotify.com thus catching all ip addresses.
Note that postgrey provides a whitelist included in the postgrey distribution. If there are many issues with spotify mails not surviving greylisting, they might be inclined to include it in the postgrey default whitelist.

5

My greylisted emails come in after a 300 second delay. Unless they’re just completely misconfigured or not legit I’ve not lost any.

6

I would agree that this is what is happening in 99% of the use cases with greylisted emails and properly configured mailservers. Normally the same mailserver is resending the message so it goes through. However the strange thing is that in this case the rejected emails were send in ± 60s intervals from different email servers. Not sure why Spotify would use a different email server to send a rejected email knowing it could create issues with greylisting.

7

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