In the meantime it is very easy to create a basic html newsletter and then install the mod here that allows html to be emailed. Then just send it through the built in Vbulletin system
If you are not good with html you can use something like Dreamweaver. Newsletters should be fairly simple and to the point anyways. Some text a picture or two and a heading at the top under your logo and bam..good to go.. Oh yeah, also include instructions how to unsubscribe and you are set.
This is what I use for html emails..works fine for me on 4.2.2
https://vborg.vbsupport.ru/showthread.php?t=232687
Just paste your html into the box in the Vbulletin email system and pick your usergroups and send..