Note: this is only applicable to Mailhandler versions 6.x-1.x and 7.x-1.x (colloquially "Mailhandler 1.x"). For a tutorial on setting up a more complex post-by-email system and mailing list (which could integrate with a forum or case tracker), using Mailhandler 2.x, see the article Setting up an email-driven workflow with attachments
How to submit Blog post by Email Note, my experiences are for simple email processing. I haven't done anything like tying an email list to a forum.
Step 1: Turn on the mailhandler module
Admin -> Modules
Click on the module
Step 2: Set up an email account to which you will send email
This depends on what you are using for a mail hosting service. I use cpanel, click on Mail , click on Manage/Add/Remove accounts.. Click on Add accounts and set up the email address and the password. For my system, the email can be retrieved as POP3. Again, this depends on the mail hosting service you are using.
Step 3: Configure the mailhandler
Admin -> Mailhandler
Click on Add Mailbox, fill in the appropriate fields.
Email address