The main problem with doing something like this is that Gmail creates a new message every time your note is updated.

Here's an example:

Create a new note, with the text "Test". This is what Gmail looks like:

> 1: [Notes] Test

Update this note to say "Test Updated". Gmail now looks like this:

> 1: [Notes] Test Updated  
> 2: Test

Update it again to say "Test Updated 2". Gmail now looks like this:

> 1: [Notes] Test Updated 2  
> 2: Test Updated  
> 3: Test

This means that if you do get forwarding to work (which there is at least one way I can think of to make it work), it will be a nightmare to deal with all the duplicates. The only way to prevent duplicates, is to never update existing Notes. You must either delete them immediately after you create them, or get in the habit of treating them as read-only. If you choose the former, you may be better off using the Evernote app or Mail app instead, both of which involve less steps.

**Update**: If you're okay with duplicates, this is how you would set up forwarding to work...

You will need the following:

 1. A second Gmail account.
 1. A way to distinguish between Notes vs. other email.

1) Since Notes that are created on the account do not respect Gmail's filter rules, you need to use a workaround. The workaround is setting up another Gmail account which will read your original account's email via POP3. As the email is being read, any filters can be applied, including forwarding the notes to your Evernote account. The problem is that since you are reading all the mail on that account, you need to make sure only notes are forwarded, which leads to point number 2...

2) There are at least two ways to do this which are guaranteed to work consistently. The simplest method is to create another (3rd Gmail account) which is used ONLY for notes on the iPhone. Since that's the only email the account will get, there's no need to setup a filter to forward the messages. You can simply forward all mail that is read from that account to Evernote (see solution A). The second method of achieving this is to continue using your normal Gmail account, but add it as a plus address to the iPhone (for example user+[email protected]). This way you can create a filter which uses the `deliveredto:` attribute to distinguish between Notes and other email (see solution B).

**Solution A: Use 3 Gmail accounts**:

You should have 3 Gmail accounts:

 - `[email protected]`: your normal email account which you are probably using.
 - `[email protected]`: an email account used ONLY for iPhone notes. Do not give this address to anyone.
 - `[email protected]`: an account which reads mail from `[email protected]` and forwards them to Evernote.

Steps:

 1. On the iPhone, do the following:
   1. Remove note sync from `[email protected]`. You will no longer be using that account for note sync, since you are creating a dedicated account.
   1. Add your `[email protected]` account, and choose to only sync notes. Do not sync mail with this account. Every time you create a note on the iPhone, make sure you choose this address. You could make it your default one.
 1. In Gmail on the `[email protected]` account, do the following:
   1. Enable POP3 (if it isn't already), choosing one of the following options:
     - delete Gmail's copy: this will cause your notes to be deleted as soon as they are saved, which will eliminate duplicates at the cost of not being able to edit notes. The second you press "done" in iPhone Notes, the message should get deleted.
     - If you don't want the above behavior, choose "keep Gmail's copy in the Inbox".
   1. Delete the 3 email messages Google sends you in the beginning. You don't want those to go into Evernote.
 1. In Gmail on the `[email protected]` account, do the following:
   1. Set it up to read mail via POP3 from the `[email protected]` account. Make sure to leave the "Leave a copy of retrieved..." setting disabled.
   1. Add Evernote's email address as a forwarding address (make sure you verify it).
   1. Choose to forward all mail to Evernote's address. I'd recommend choosing the "delete Gmail's copy" option here.

**Solution B: Use a Plus address**:

You should have 2 Gmail accounts:

 - `[email protected]`: your normal email account which you are probably using. This will be used both for notes and normal email.
 - `[email protected]`: an account which reads mail from `[email protected]` and forwards them to Evernote.

I will also refer to the account `user+[email protected]` below. This is the same account as `[email protected]`, but adds a plus so that you can differentiate between iPhone notes and email.

Steps:

 1. On the iPhone, do the following:
   1. Remove note sync from `[email protected]`. You will no longer be using that account for note sync, you must use the plus account.
   1. Add your `user+[email protected]` account, and choose to only sync notes. Do not sync mail with this account. Every time you create a note on the iPhone, make sure you choose this address. You could make it your default one.
 1. In Gmail on the `[email protected]` account, do the following:
   1. Enable POP3 (if it isn't already), choosing to "keep Gmail's copy in the Inbox".
 1. In Gmail on the `[email protected]` account, do the following:
   1. Set it up to read mail via POP3 from the `[email protected]` account. Make sure to leave the "Leave a copy of retrieved..." setting disabled.
   1. Add Evernote's email address as a forwarding address (make sure you verify it).
   1. Create a filter which matches `deliveredto:user+[email protected]` and forwards the message to Evernote. I'd recommend also choosing to delete the message.
   1. Create a filter which matches the opposite `-deliveredto:user+[email protected]` and just deletes the message.

Let me know if you need any clarification.

One other thing to note is that since both of the above methods rely on reading the mail via POP3, it won't happen instantaneously, and can even take up to an hour. See [this post][1] for ways of speeding that up.


  [1]: https://webapps.stackexchange.com/questions/1811/can-i-control-how-often-gmail-polls-pop3-accounts-for-incoming-mail