I would encourage the client to use a third party service such as CampaignMonitor or MailChimp. This will give you more reliable deliverability, excellent reporting and list management, as well as safeguarding your domain name against ISP blacklisting for unsolicited spam.
You can then integrate these services with EE. For example, something I've done before is to create an 'emails' EE channel and use relationship fields to pull in various articles and news items into an html email web page, complete with all the necessary CampaignMonitor tags for dynamic salutations, unsubscribe links and all the legal stuff that you are required to put on such mailings. CampaignMonitor then allows you to import the email directly from the web page.
I believe there are some ways you can integrate these services more tightly, but I've found this to be sufficient for my needs.