<span>
The <span> element is a generic container with no special meaning.
Recommendation
It is highly recommended for an email client to support the <span> element.
Impacts
Progressive enhancement
In the context of email in which some HTML elements are expected not to be supported by some email clients, supporting <span> may allow the developer to code the email with progressive enhancement in mind and implement an alternative more basic experience.
Accessibility
While it does not have any semantic meaning on its own and is mainly used for styling, adding the role tag attribute can change the semantic meaning of a <span>. Supporting <span> allows the developer to group elements that semantically need to belong to the same parent or wrap some content that needs to belong to an element with a specific role.