Version 1.3.x breaks image mimepart values for images

[chrisdrydenaltmetric]

Application version: Rails 7.2.2
Affected mailgun-ruby versions: 1.3.1, 1.3.2

Upgrading mailgun-ruby from 1.2.16 to 1.3.x leads to corrupted mimepart values for attached images. This happens downstream of a rails application since the rails logs display the correct values on sending the email.

Rails application logs:

----==_mimepart_67a0ddc39ae97_184c140021067
Content-Type: image/png;
 filename=source-msm.png
Content-Transfer-Encoding: base64
Content-Disposition: inline;
 filename=source-msm.png
Content-ID: <[email protected]>
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Mailgun logs for the same email:

--fd83aab1b2a330ff916b4a6699d19c4e4e3a8903d646810b4f027f1464d7
Content-Type: application/octet-stream; name="."
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename="."
Content-Id: <.>

[koenhandekyn]

confirming, we had to step back also. took a while before we where able to point it to the version bump.

[wout]

Same here. ActionMailer adds the attachments (CSV in our case), but they don't arrive in the final email. Downgrading to v1.2.16 fixes the issue.

[alex-leb]

Hello @chrisdrydenaltmetric. Thank you for submitting this issue!

It looks like a duplicate of #340.

We are going to fix it in the upcoming release.

Sorry for the inconvenience!