Been researching about this and would like to hear opinions.
Some clients can't afford anything but shared hosting and I actually agree on several cases because it makes no sense to pay more, they don't need big stuff, superfast servers, etc, it's not critical for them. BUT they need their own email system and that's the expensive thing considering private hosting.
When a client is located on a shared server, all the sites hosted there share the same IP and the sins of one client will hurt the others (IP reputation), yes you can buy a private IP address but that doesn't mean your email will use it. Suddenly you receive no replies because clients are getting the mails directly into the junk folder (if delivered at all).
Google offers G mail to deal with this, not only a gmail account, they can take care of your email after tweaking your server config: G becomes your email provider, or sort of. BUT you become one of many delivering peacefully all your data to G. Free? ha, there is no such thing as free in this world. This is not something I advice to do, sure you might disagree.
You could use a third party mailing service for bulk mails but those suitable for a small business normally insist on double opt in when importing an existing, opted in, mailing list. That's a great way to give a mailing list a drastic pruning.
Other than that I would say choose your hosting service very very carefully.
I have had no problem with shared hosting when sending out bulk mailings through my current host.
When I first started I was using "free" hosting from my ISP and it wasn't worth the money. Newsletters were regularly bounced because the IPs were blacklisted.
Doesn't Google append the "on behalf of" message to the email "FROM" part?
1and1 shared server email has been sucking for the past couple months because their IP ranges have been getting dropped into spam blacklists. The workaround is to use the SMTP server of another host provider that isn't as big.