When word wrapping is on, using this reply or forward template:

?d{>Sent %D{%A %d %B %Y at %R}
}?f{>From: %f
}?t{>To: %t
}?s{>Subject: %s
}?c{>CC: %c
}
%q

If one of the %fields is longer than the wrapping limit, it wraps correctly but the next line is not separated by a line break.

You expect :

>Sent Tuesday 02 April 2025 at 16:20
>From: John Smith <JohnSmith@dummymail.co>
>To: Alice <Alice@dummymail.co>, Bob <Bob@dummymail.co>, 
>Jack <Jack@dummymail.co>
>Subject: New stuff!

But if for instance the To: line is longer than the wrap limit, the Subject: line gets aggregated to the previous one:

>Sent Tuesday 02 April 2025 at 16:20
>From: John Smith <JohnSmith@dummymail.co>
>To: Alice <Alice@dummymail.co>, Bob <Bob@dummymail.co>, 
>Jack <Jack@dummymail.co> Subject: New stuff! <--- Notice also the lack of '>' before 'Subject'.

Adding a simple \n to the template does not work, neither between the two fields, nor inside one : "?t{>To: %t\n}", "?s{\n>Subject: %s}" and "?t{>To: %t}\n?s{\n>Subject: %s}" are all ineffective.