I've searched for a long time, but I can't find anything that helps.
Basically, when a user is created, I input a username, password, and email address. Then, when I check the "notify user of new account" box and save the user, I go to a white screen with plain text saying: "Invalid address: You must provide at least one recipient email address." I checked the logs and the email doesn't have a "to" address.
Also, when I do login (or masquerade) with the new user, the site has a prompt stating that I need to provide a valid email because there isn't one for that user, despite a valid email address having been input at the time of creation. When I enter the email address in this prompt, then it is saved to that user (meaning I go to the edit tab of a user and see the email address there).
Everything I've come across says it could be one module or the other... but I don't have any of those modules referenced.
I have SMTP authentication support. I have Simple Mail.
I am able to send out test emails and other mails (i.e. from a triggered action), but not to notify users of a new account.
I'm sorry if this has been covered elsewhere... I've looked but haven't found anything that works.
Also- I'm working with Drupal 6.
It's similar to this issue: to email address not populated