Is this legal?

If you don't do anything illegal to collect the emails, then you will have no problem.

Good Luck,
Leonardo.

Been there, done that.
Are we really talking about legality here? Because believe me it will not work.
Even if you think that you are not spamming, you are just most likely to end up on SPAM folder.

Hey Blindbiz has your client thought of enrolling an email marketing company? It will come at a fraction of a cost and help a great deal in adding more email lists, thus nothing to worry about legality and hassle-free. This is in addition to the emails you get via 'opt in' and and 'call to action' tabs on social media. Plus email marketing cos have free plans to try. I am using Ariticmail for my fashion store, they help me with various options apart from mysql database support to import newer email lists.

That really depends, where are you getting the email addresses? Is the owner of that business considered to be a user on the site you get them from? If so then no (this applies to whois as well, the business is a user of the registrar.) Are you going to their own site and getting their addresses from there? Well that's grey area. On their own site do they loosely give permission? On their own site do they say "email us here." I suggest you talk to an attorney but mine says that's compliant. If on their own property they encourage emails, that's kind of their problem.

Read the law very carefully, I'm sure there's some local biz guys who are making a complete killing and they are doing it legally. Not some guide, not some BS webpage, get a copy of the actual law and look it over as carefully as you can. I know there are some local biz guys who are making a killing who are not complaint and will never get in trouble. Do you want to follow in their footsteps? That's up to you.

If the emails are coming from a data provider who tells you they signed a contract granting permission, that's totally compliant as well. This doesn't sound like it's the case.

If you can't prove where you got the addresses in court, with timestamps and screenshots, I don't suggest you do it.

i agree that as long as you don't collect the emails illegally you are good, and the receivers should have an option to opt out of the mailing list when ever they like.

If they have not given you their permission or subscribed to your list, this is called SPAM and it is useless in my view.

If you are collecting those emails in natural way then its not ilegal.
but be aware of any type of spam or illegal activities.