laravel 5.4 embed image in mail

It seems that the older $message->embed doesn't work nicely with Markdown emails. Like you mentioned in the comments it seems broken since 5.4

But you could just try it like this inside your markdown email:

This is your logo 
![Some option text][logo]

[logo]: {{asset('/img/official_logo.png')}} "Logo"

Like shown here:

Asset function reference:

Try this:

<img src="data:image/png;base64,{{base64_encode(file_get_contents(resource_path('img/email/logo.png')))}}" alt="">