How can I force a specific SMTP 4xx error (452 4.2.2 mailbox full) to become a HardFail instead of SoftFail?

[kewayne]

I am running Postal (Docker installation) and I am trying to customize the delivery behavior for a specific SMTP response.

Currently, when delivering to Gmail, I get this:

452-4.2.2 The recipient's inbox is out of storage space. Please direct the recipient to
452 4.2.2 https://support.google.com/mail/?p=OverQuotaTemp

Postal correctly treats this as a SoftFail because it is a 4xx response, but in my use case I would like this specific error (452 4.2.2 mailbox full) to be treated as a HardFail instead of retrying.

I found the logic in:

/opt/postal/app/app/senders/smtp_sender.rb

specifically the Net::SMTPServerBusy rescue block, where Postal creates:

create_result("SoftFail")

for temporary SMTP errors.

Has anyone implemented a clean way to override this behavior?

My goal is:

Keep normal 4xx SMTP errors as SoftFail
Only convert 452 4.2.2 mailbox full / OverQuotaTemp responses into HardFail

I am wondering if there is a recommended way to do this in Postal, or if modifying smtp_sender.rb is the correct approach.

Thanks!

[willpower232]

Unfortunately this would require a code change as you suggest, would be good to see a PR for it though.

That said, I did just yesterday see a case where an email was rejected for the inbox being full and then later that same day, successfully delivered so it being temporary does happen 😅