I created an emailtemplate, with our logo and social media buttons as clickable images. The template also has an attachment.
When I send this template the mail looks good in outlook.

But on my iPhone 6 it is shown as plain text, so the clickable logo and social media buttons are replaced by hyperlink-text.

When I send the same template without the attachment the mail also looks good on my iphone.

(How) can I send an emailtemplate with attachment that will not be shown as plain text on mobile devices?