If you were previously using the Email feature in the task view in informant you'll see that has been disabled in version 5.72 due to syncing issues it was causing for most users.

In its place we recommend you try the Informant Sync Email To Task feature.   Each Informant Sync user is able to generate a private email address that is specific to their sync account. All emails sent to it (regardless the source) will be converted into a Task for that user.

To use this feature simply go into the Settings for Informant Sync on your device. For example on iOS go to Settings->Sync Accounts and then choose the Informant Sync account. Then hit Sync Options and scroll down to the bottom.  If you've never set up Informant Sync to receive emails you will see a line that says "Task Email Not Configured".  You need to tap on that and have it generate a new email address.  If you have already generated an email address for your sync account, it will show you your email address there.

Now just send emails to the email address you get.  

The subject line of the email becomes the Task title, and the message body becomes the Task note.  You can even set certain parameters of the task by using a special syntax. The syntax is used within the title of the email.
  • Priority - The default priority is "Normal". Use the ! character to indicate how important the task is.
  • Due Date - To set a due date use the # symbol and then type a date.
  • Start Date - To set the start date use the > symbol and then a date. For example: ">today".
  • Star - To star a task use the * symbol by itself. For example: "My Task *".
  • Project - To set the project use the * symbol and then type the name of your folder. For example: "*Housecleaning".
  • Context - To set the context use the @ symbol and then type the name of your context. If your context is actually named "@HomeStuff" then you would need to type "@@HomeStuff" to set the context, since the first @ is the symbol and the second @ is part of your context.
  • Status - To set the status use the $ symbol and then the status. For example: "$Next Action".
  • Tag - To set the tag use the % symbol followed by the tag or tags that you want to add. For example: "%Family,Cleaning".
  • Note - The body of the email will become the note of the task. You can prevent email signatures or other parts of the email from becoming part of the note by typing -end- where you want the note to end.
Each new piece must be separated by a space followed by the special character. As an example, the following subject line would create a Task called "Clean garage" starting today, due Mar 20, medium priority, with Family and Cleaning Tags, in the Housecleaning folder, and HomeStuff context:

Clean garage >today #3/20 !! %Family,Cleaning *Housecleaning @HomeStuff