message-send freezes emacs

[Maverickzero]

I'm using message-send to send my org-msg e-mail.s It does work perfectly, but every time I hit the send button my emacs instance freezes for a while until the mail is finally sent. My current org-msg configuration is the following:

(after! org-msg
  (setq mail-user-agent 'mu4e-user-agent)
  (setq org-msg-options "html-postamble:nil H:5 num:nil ^:{} toc:nil author:author email:nil \\n:t"
        org-msg-startup "hidestars indent inlineimages"
        org-msg-greeting-fmt "\nHi%s,\n\n"
        org-msg-greeting-name-limit 3
        org-msg-default-alternatives '((new . (text html))
                                       (reply-to-html . (text html))
                                       (reply-to-text . (text)))
        org-msg-convert-citation t
        org-msg-signature "
#+begin_signature
<signature>
#+end_signature"))

Any idea on what the issue could be?