Configuring modules for email sending and formatting is a pain and confusing. Most mailing modules rely on Mailsystem module to help configure this.
In D7 Mailsystem 3.x there's an improved method of doing this by using a delegator class. https://www.drupal.org/project/mailsystem/issues/1508104. I propose that the class and related functions be put into core. The UI can stay out of core.
This will help any combo of modules share the responsibility of sending emails. One module can be used for formatting HTML (MimeMail, HTMLmail) and another for sending (SMTP, PHPMailer, Postmark, SendGrid, ...). The popular modules can then use the new class to allow other modules to share in the work and also provide a simple UI (without needing to install Mailsystem if they don't need that extra power).
Recent comments
As I work through things I flush the caches after every change I make. As far as I can tell I have the custom module in the correct place (/modules/custom/fix_zero_search) and the file...
custom module not showing up in modules list
If you haven't already, flush all the caches. If it is in the modules folder whether directly or in a custom folder it will show up. If not, something else is wrong with your site; check...
custom module not showing up in modules list
Awful idea! That's not how modules get installed! The number in db indicates the installed state and schema version. You're not supposed to fiddle in the database directly. There's an...
custom module not showing up in modules list