user-agent is missing in sent email headers

[jindam.vani@disroot.org]

please excuse, i am posting here suggested by akib 
on mastadon.[1] i am running emacs on debian 
bullseye on userland.[2] when i send mail using 
gnus and the "User-Agent: Gnus/5.13 (Gnus v5.13) 
Emacs/27.1 (gnu/linux)" is not added in sent 
email headers. 

when i click t in nnfolder+archive:sent.2022-12, 
it shows "User-Agent: Gnus/5.13 (Gnus v5.13) 
Emacs/27.1 (gnu/linux)", before it was showing 
only from, subject, to, date.

conversation between akib and me on mastodon.[2]
what am i doing wrong?

;; .gnus
(setq gnus-select-method '(nnnil ""))

(add-to-list 'gnus-secondary-select-methods
             '(nnmaildir ""
              (directory "~/.Maildir/")
              (get-new-mail t)
              (directory-files nnheader-directory-files-safe)))

(setq mail-user-agent 'gnus-user-agent)
(setq read-mail-command 'gnus)

(setq mail-sources
                  '((pop :server "disroot.org"
                         :user "jindam.vani@disroot.org")))

(setq send-mail-function 'smtpmail-send-it)
(setq message-send-mail-function 'smtpmail-send-it)
(setq smtpmail-default-smtp-server "disroot.org")

(setq smtpmail-stream-type 'ssl)
(setq smtpmail-servers-requiring-authorization ".*")
(setq smtpmail-smtp-service 465)
(setq smtpmail-starttls-credentials '(("disroot.org" 465 nil nil)))

;; .emacs
(setq make-backup-files nil)
(setq create-lockfiles nil)
(setq auto-save-default nil)
(setq frame-title-format "%b")
(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(canlock-password "ff816ad05b9a5accc83c04cdffdc44e7854b5ab8")
 '(debug-on-error t)
 '(display-battery-mode nil)
 '(initial-buffer-choice "~/")
 '(send-mail-function 'mailclient-send-it)
 '(smtpmail-smtp-server "disroot.org")
 '(smtpmail-smtp-service 25 t))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(default ((t (:family "fixed" :foundry "misc" :slant normal :weight normal :height 231 :width normal)))))
(add-to-list 'load-path "~/.emacs.d/jl-encrypt")
(require 'jl-encrypt)
(require 'epa-file) (setq epa-file-encrypt-to "46BB3F32")
(setq mail-user-agent 'gnus-user-agent)


[1] https://c.im/@jindam_vani/109516965307129546
[2] https://c.im/@jindam_vani/109515651458422170
[3] https://github.com/CypherpunkArmory/UserLAnd

i am sending this email using gnus emacs.

regards,
jindam, vani