Recently our ESP, not CM unfortunately :( has stopped supporting <style> tags which have broken some of our responsive templates relying on @media queries. When asked why I was puzzled by there response:
"The decision about stripping certain HTML tags has been made on the basis there are very few ISPs which support them. It's still very common that ISPs keep stripping the unsupported tags (like style) even though a message was sent with them.
Stripping tags is also important for deliverability. Some ISPs may consider your messages as spam and filter them out."
Is this a valid reason? As far as I was aware it isn't a spam issue, they are supported by some clients and just get stripped out or ignored by others. It will make our responsive approach via @media queries impossible if this is unsupported.
Do they also strip <link> tags? If not you could try putting your styles in an external stylesheet.
To me it sounds like your ESP isn't interested in good looking emails, without style tag support you have no way of easily dealing with css quirks such as resetting line heights in Outlook.com. You may want to consider switching ESPs if it remains a problem.
Strictly speaking, if they support inline styles then there is no reason not to support style tags afaik.
Just been doing some testing from your suggestion and it look as though that linking to an external stylesheet is working. They don't strip out the <link> tag. I need to conduct further testing on this though...
Your ESP isn't interested in good looking emails
Yes, this quickly the conclusion we are coming too. It's very odd this isn't supported, as inline styles are...
Thank you for your help.
Interestingly enough in the ESP's own email template builder they use a <style> tag and @media queries in their coding. Starting to think there's a double standard here...
I had an ESP I was forced to use that stripped out the conditional formatting in VML code. It meant that I couldn't use bulletproof buttons in older versions of outlook.
As your <style> problem, it's usually wise to inline styles anyway for maximum compatibility. You can use http://premailer.dialect.ca/ to automatically do this for you. The problem here is you'll be stuck without media queries.
All the best.