Why is my email being sent out from an Unknown Sender?

The from portion of the email is saying: From: UnknownSender@UnknownDomain

Could it have to do with this line my 开发者_如何转开发in mailer file?

  default :from => "DreamStill"

I'm using the SendGrid add on for Heroku. It seems that DreamStill showed up for some addresses, and unknown sender for others.

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Specify a valid email address for your "from" field, such as:

:from => "DreamStill <justin@dreamstill.com>"

The way it's being displayed when received by users may very well be dependent on what application is displaying the email, such as Outlook, Gmail, etc.

There's also a number of hurdles, like spam filters, anti-virus scanners, services such as MessageLabs, that email goes through these days. Any one of these could be causing it. Basically, specify a valid email address for the "from" field, and try again.