Heyt here. Nice to meet you.
My name is Thei and I'm a Dutch software developer. What you need to verify e-mail addresses is called a regular expression (regex). Combined with a scrip in, for example, PHP, it can verify all addreses in your list in a matter of (milli)seconds. I believe this job can be done in one day. Before I start I have two more questions:
1. You say you want to support Gmail, Hotmail, Yahoo and 'other emails providers'. Does that mean you want to support ALL other e-mail providers, as long as the address is in valid format? Or do you want to check for specific providers? In the latter case, I would need a list of all the accepted providers.
2. Do you want to run this script once on a single CSV list? Or should it be reusable (for example: the ability to upload another CSV list somewhere in the future). My proposal is based on the first option, but the latter is possible as well.
Looking forward to hearing from you,
Thei Savelkoul