E-Mails are sent as attachments after upgrading to Magento 2.3.4
• Magento2
We recently updated a Magento shop to latest version Magento 2.3.4. First, I was wondering that order confirmation mails were sent as attachments. Meaning there was no content anymore, everything was placed in a file called attachment.html.
After analysing this issue, I stumpled upon this issue. Reason was a newly introduced $part->setDisposition(Mime::DISPOSITION_INLINE);. Thankfully, this could be patched by applying this commit.