I'd concur with Lauren.
It depends on what you call huge.
If you send out a huge mail campaign using your Cpanel server you're almost likely to run into problems.
1. You run the risk of becoming blacklisted as a spammer.
2. If you get blacklisted, you'll have problems sending legitimate emails
3. If you are on a shared server, you'll potentially also blacklist everyone else who shares that server.
4. You'll probably run into issues with your hosting provider and could get your account suspended.
5. Your hosts may have a limitation on how many emails you can send anyway, in which case your whole email campaign might just fail.
Mailchimp gives you something like 2000 free credits.
Moosend is cheaper if you have to pay.
There are lots of mail sending companies out there.
Whilst it goes against the grain of paying for something that you can potentially get for free, you are likely to run into issues.
There was another option that I looked at, which was to lease a cloud server.
This could be done on a monthly basis for small costs.
Even though my mailing campaign is legitimate, It wouldn't matter too much if I blacklisted it, as I'd only be using it for a few days.
However I decided that this was probably unethical.