Sending mail in Redmine

Question

I have updated my Remine on servers from 2.3.0 to 2.4.1 and one (and only one of them) stops sending mail. If I was switched it back to 2.3.0 version, all works fine.

I am going to try to debug the code and just wondering which file in source code will be a good starting point to it ?

I have found notified_users(), recipients(), each_notification() in Issue model, but where is a code line which send email ?

Updated:

When I edit issue I get next message on console:

  Rendered mailer/_issue.html.erb (2.2ms)
  Rendered mailer/issue_edit.html.erb within layouts/mailer (4.8ms)

Sent email "[Redmine - ÐапÑÐ¾Ñ #13757] test" (26ms)
  to: mymail@gmcs.ru
Date: Thu, 05 Dec 2013 17:34:07 +0400

....
cG9ydC5nbWNzLnJ1L215L2FjY291bnQ8L2E+PC9wPjwvc3Bhbj4KPC9ib2R5
Pgo8L2h0bWw+Cg==

----==_mimepart_52a080cfa4564_af93f8d53ef7714733eb--

Email delivery error: wrong argument (NilClass)! (Expected kind of OpenSSL::SSL::SSLContext)
   (5.9ms)  COMMIT
Redirected to http://vm-mecomstracker:90/issues/13757
Completed 302 Found in 574.3ms (ActiveRecord: 33.5ms)

Answer 1

I think you should look at app/models/mailer.

For example notified_users is used here

If update breaks sending emails I suggest to review config files, for example config/configuration.yml.example and check fresh issues on redmine.org