Solves an issue with Sendgrid
https://docs.sendgrid.com/for-developers/sending-email/send-mime-messages-with-sendgrid
This error happened when using Webscale which was uses SendGrid for email relay services.
SendGrid does not handle Content-Transfer-Encoding: quoted-printable and the extra CRLF characters breaks the source content.
For example the vendor/magento/module-user/view/adminhtml/email/password_reset_confirmation.html renders as:
First Last,=0A=0AThere was recently a request to change the passwor=
d for your account.=0A=0AIf you requested this change, reset your passwo=
rd here:=0A=0Ahttps://domain.com/admin/admin/auth/=
resetpassword/?id=3Dtoken
you did not make this request, you can ignore this email and your passwo=
rd will remain the same.=0A=0AThank you,=0AStore Name
This is technically valid for quoted-printable but it breaks SendGrid body processing
This module allows you to choose 7bit for the default email encoding on magnetos transport builder.
By default this module will choose 7bit but you can test it by switching back to quoted-printable with the admin config for this module.
composer require human-element/module-configurable-email-encoding