Online newsletters/ezines number in hundreds of thousands, and total is ever increasing.
How can, and will, you compete?
If you want your offering to stand out, plug it into 5 "P's" formula ...
Purpose - Are you giving your target market what they want? Make sure that you provide fresh content, updates on newly released, related resources, etc., geared to specific needs and interests of your subscribers.
How do you find out what they are? Ask them (polls, respond requests)! You may also want to look at your industry's "heavy hitters". Subscribe to, and study, their offerings. Applying techniques that work for them can help you, as well.
Personality - You simply must develop your own style if you're going to succeed.
This is of extreme importance.
Lose hype, and interact with your subscribers as if you were talking to each one honestly, personally. This will help build a bond of trust, and aids self branding.
Personalize - I'll say it again, as it's worth repeating ... Interact with your subscribers as if you were talking to each one, personally! Use name tags, if this is an available option, whenever possible (I prefer "first name" only. Having first AND last looks too automated). If it isn't, you may want to change your delivery method to a service that allows them.