Replace link with button in mailing options

app/views/dashboard/mailing/_mailing_options.html.erb

@@ -5,8 +5,7 @@
                 class: "button expanded" %>
   <% end %>
 
-  <%= link_to t("dashboard.mailing.mailing_options.send", address: current_user.email),
+  <%= button_to t("dashboard.mailing.mailing_options.send", address: current_user.email),
                 proposal_dashboard_mailing_index_path(proposal),
-              method: :post,
                 class: "button expanded" %>
 </div>

spec/system/dashboard/mailing_spec.rb

@@ -13,11 +13,11 @@ describe "Mailing" do
   end
 
   scenario "Has a link to send the mail" do
-    expect(page).to have_link("Send to #{proposal.author.email}")
+    expect(page).to have_button("Send to #{proposal.author.email}")
   end
 
   scenario "User receives feedback after the email is sent" do
-    click_link "Send to #{proposal.author.email}"
+    click_button "Send to #{proposal.author.email}"
     expect(page).to have_content("The email has been sent")
   end
 
@@ -31,6 +31,6 @@ describe "Mailing" do
     click_link "Preview"
 
     expect(page).not_to have_link("Preview")
-    expect(page).to have_link("Send to #{proposal.author.email}")
+    expect(page).to have_button("Send to #{proposal.author.email}")
   end
 end