Sure. Go to the OmniFocus app on your Mac, under the Help menu, type the words "processing mail" into the search box. Sometimes it doesn't give you results the first time, but if you persist, there will be one called "Processing Mail messages into actions" and that tells you what you need to know. I've included an unformatted version here:
Processing Mail messages into actions
When it’s not convenient for you to put data directly into OmniFocus (like when you’re sitting at a someone else’s computer), you can send a specially-formatted email to yourself and OmniFocus will process it later. To set it up, use the OmniFocus Mail preference pane.
To turn on Mail processing, select the Add Mail Rule to create OmniFocus actions checkbox.
Once the Mail Rule has been added, you can tell OmniFocus what kind of messages to look for. One way is to look for messages that have +omnifocus before the @ sign in the destination address, as in email@example.com
. If your mail service is properly set up for this type of addressing, the message arrives in the correct mailbox as if the plus sign and the extra word were not there, but they act as a label for special handling. The other way is to look for messages whose subject line begins with certain characters, -- by default.
If you want to keep the messages that OmniFocus processes in a certain mailbox, select Archive processed messages and choose a mailbox. Otherwise, they are deleted.
The Allowed From addresses list is automatically filled with any email addresses on the “Me” card in Address Book. You can add more addresses, if you expect to be sending yourself OmniFocus actions from any other accounts.
The way that messages are processed is pretty detailed, and you have a lot of power in how you can format your items:
The subject and body of the message are joined into a single block of text.
The first line and any other lines starting with -- (double-hyphens) become new actions. Other lines become notes for the preceding action.
To specify a project, use > (greater-than sign) or :: (double-colons), followed by a project name or abbreviation. The colons are nicer for the iPhone because they are on the first shifted keyboard rather than the less-accessible math keyboard. The project string is matched exactly as if it was entered in a project cell in OmniFocus.
To specify a context, use @ (at sign), followed by a context name or abbreviation. Like project names, the context name is matched exactly as it would be in OmniFocus.
To enter start or due dates, use # (number sign), followed by some date expression. The same expressions you use in OmniFocus (tomorrow, 9-30-2008, 2w, and so on) can be used in mail messages. If there is only one date, it becomes the due date. If there are two (each with its own number sign), the first becomes the start date and the second becomes the due date.
To enter a time estimate, use $ (dollar sign—time is money) followed by some duration expression (like 5m, 1h, and so on); you can use the same duration expressions that you use in OmniFocus.
To flag the action, use ! (exclamation point) at the end of the action title.
You can also add a note on the same line as an action title by separating them with // (double-slashes). Anything after the double-slashes becomes a note, but double-slashes in a URL like omnigroup.com don’t count.
Here are some examples of actions you could send to yourself:
Note note note note note la la la
note la la
-- Another Action > Project 2 @ Context 3
I have empty lines in my note
-- Action 3 > Project 1 @ Context 1 // Same-line notes too, if you are into that kind of thing
-- Action 4 #friday // Due Friday, because I only entered one date
-- Action 5 #monday #friday // Starts Monday; due Friday.
-- Action 6 #monday # // Starts Monday; no due date.
-- Action 7 :: Project 3 // Written on my iPhone; colons work in place of greater-than sign.
--Action8>p2@c2#2d$5m//no spaces needed, nor full names