Hi Jean, Thanks for additional info. This helped discover a bug, which I fixed in commit b6818d6d3c. Please pull and rebuild mailutils, then apply the attached patch to rcd-mail.el and try sending mail. Let me know if it works for you.
Regards, Sergey
--- rcd-mail.el.orig 2021-06-06 21:32:16.187977171 +0300 +++ rcd-mail.el 2021-06-06 21:32:48.821977167 +0300 @@ -87,10 +87,13 @@ Optionally FROM-NAME may be suppplied." "Return list with \"mail\" program arguments with TO-EMAIL. Optionally provide TO-NAME, the name of recipient of email." - (let ((to-name (replace-regexp-in-string "," " " to-name))) - (cond ((and (stringp to-name) (string-match "@" to-name)) (list to-email)) - ((not (seq-empty-p to-name)) (list (concat (rcd-rfc2047-encode to-name) " <" to-email ">"))) - (t (list to-email))))) + (cond + ((and (stringp to-name) (string-match "@" to-name)) + (list to-email)) + ((not (seq-empty-p to-name)) + (list (concat "\"" (rcd-rfc2047-encode to-name) "\" <" to-email ">"))) + (t + (list to-email)))) (defun rcd-mailutils-mail-sendmail (sendmail) "Return list with \"mail\" program arguments supplying \"SENDMAIL\" program."
