Sit and think of all the times you have shared with your love one. This brainstorming will get you into a romantic mood and help you type what you want to say. Write it out on paper before or do a draft in Word. Just be true to your feelings and your heart.
Go to a card store or a store that also has cards. See how the verse is phrased on the cards and if any cards apply to how you feel. These romantic cards can give you the inspiration, and you can use this type of wording in your email. Read and research if it does not come easily for you, and remember to make your email genuine.
Visit your local library and check out the poetry section. You might become inspired by the many famous poets out there and write your loved one a poem in the email.
Use e-cards as romantic emails. With an e-card, you can add your personalized message on a romantic card for your sweetheart. There are a variety of ecard websites out on the web, so just do some research to find the one you want to send your love.