Creating a New Email: HTML Upload vs. Send From ESP
We highly recommend sending in your email directly from your Email Service Provider (ESP) to start an email in Litmus, as many times ESPs can change/alter your HTML template before your final send. Since Litmus does not alter your HTML code, you may see a difference between an HTML-uploaded copy versus what you see on your ESP’s sent copy.
If you send in your email directly from your ESP, you will see exactly what your subscribers see when they receive your campaign. You can easily send in an email test to Litmus from your ESP by using Litmus’ email addresses in the test/preview email send before sending your campaign to your subscribers.
Sending from your ESP is also best when using the spam filter analysis tools, as this will provide the most accurate reputation scoring for your email.