Copy Named Range cell values with line breaks into html/email body [duplicate]

Question

I am trying to copy the named range cell messageHeader into a HTML template to send an email.

The cell looks like this in Google Sheets:

The console also displays it correctly:

However, as soon as the HTML template processes this named range value, it flattens all line breakers in cell into a single line, and the email arrives like this.

The code:

const messageHeader = wsS.getRange("messageHeader").getValue()

HTML template code:

<div class="main"><?= messageHeader ?></div>

How can I copy line breaks into HTML teamplate that will show up correctly in the email?
HTML has <br> for line breaks, but I have no idea how to implement this.
Adding <br> in the cell still goes out as plain text in the email instead of new line.