Automated emails are not being sent upon new user registration and password reset.

Problem

• Automated emails are not being sent (i.e. new registration welcome email, password reset email).
• I do receive the "A welcome message with further instructions has been sent to your e-mail address." and "Further instructions have been sent to your e-mail address." alert immediately following the registration/password reset form submission.
• The new user does show up on the /admin/people list, with Last Access as "never".
• I unsuccessfully attempted new user registration with several different Gmail and 10minutemail.com email addresses.
• The site email is a Gmail address.

Environment

• Drupal version 7.43
• Drupal Commons 7.x-3.35
• Chaos tool suite (ctools) 7.x-1.9
• Email Registration (email_registration) 7.x-1.3
• Entity API (entity) 7.x-1.7
• Entity tokens (entity_token) 7.x-1.7
• Registration (registration) 7.x-1.6

Is there a known solution to this problem? If not, is there a way to complete the new user registration (i.e. have the user pick a password) at the user/register screen? Would it be possible to send out password reset emails some other way?

I'm new to Drupal, so please let me know if there is a debug procedure that I can follow to improve this support request. Thank you so much!