This is the error:

The e-mail could not be sent.
Possible reason: your host may have disabled the mail() function…

When you trying to access your blog or your administration dashboard, you get nothing but white screen and above message. You probably contacted your hosting company but most of the time they can’t figure out what is wrong with your WordPress blog.

It’s not that hard to fix, if you diagnose it properly. Let me assure you that you don’t have to reinstall your WordPress blog.

There are 3 possible conflicts that could have caused this error.

1. Trackback or comment conflict.
2. User password conflict.
3. e-mail php/SMTP conflict

Let’s fix this mysterious error.

• Trackback or comment conflict:

You probably received a trackback comment and it jammed your database. If your blog crashed after you moderate a trackback comment or a spam comment, your error will fit into this conflict category. To fix this problem you need to login to your phpmyadmin in your MySQL database. Here’s the step by step instruction: How to delete comments using phpMyAdmin.

How to prevent trackback comment conflict?

If you have installed a plugin called “Comment Relish” by Justin Shattuck, it could be one of the source of this problem. Deactivate the comment relish plugin until author address this problem. (/wp-content/plugins/comment-relish.php)

• User Password Conflict:

Your password or “wp_users” may be corrupted. To fix this problem you need to login to your phpMyAdmin in your MySQL database. Here’s the step by step instruction: How to change password using phpMyAdmin.

How to prevent user password conflict?

Create an extra admin user for yourself, just in case the first one goes bad. Always back-up your WordPress core files. You can use WordPress database backup plugin.

• e-mail php/SMTP Conflict:

If your hosting server that has the php mail function disabled, you might end up with this error also. Go to WordPress plugin directory and find a suitable SMTP mail plugin. (Many hosting providers, including 3Essentials require SMTP-auth to send mails, and WordPress's does not natively support this as it uses PHP's mail function, which by default, does not support SMTP-auth. See here for a discussion of SMTP-auth requirements on 3Essentials hosting)

If you tried all 3 and still get error, please post your problem on WordPress Forum. You’ll get plenty of help from contributors.