Is it ever okay to send marketing emails to a list of emails that didn't request them?

Is it ever okay to send emails regarding your start up to a scraped or purchased list?

Is this okay in any scenario? For example, if my start up sold software for managing mobile-hairdressing businesses for woman that were 35 years old from California, and I had a list full of people that met that precise description, so I know my email would be relevant to them?

I suspect not, but I have little experience in this area.

Let's start with getting some basics out of the way, sending unsolicited emails has a very very low conversion rate, is not allowed on most 3rd party mailing systems and may depending on how you acquired the emails be against the law in your country or the country the mail server thats sending the email resides in.

i.e if you expect a return from this you have to do volume and we are talking thousands upon thousands. So using your example there simply won't be enough people to email to get many conversions.

Also emailing on a large scale is costly, even if your mail is legitimate a small percentage of people will complain it is spam regardless given most mailing services won't allow bought lists you will have to manage the mail server(s) (you will need more then one or your mail will go straight in the spam bin).

So to reach the volume needed requires infrastructure, time, effort and some money for little to no return except on a massive volume level. So it's probably not worth it regardless however hot or tight the leads might be.

Next comes the legal issues, most countries now have some rules regarding unsolicited emails and in most cases they are not as tight as most people think for example the US can-spam act does allow what I consider an unsolicited emails you just have to be careful how you do it.

You can even in certain situations use a paid for list however you have to know how every user got on that list, know that they opt'ed into that list not once but twice and knowingly gave their consent for that list to be passed on to you, and have not subsequently opt'd out of that list through the original or any of the third parties they passed the list to. Given the only way to truly know any of this is to be the original list owner you are in effect putting your trust in the owner of the list AND the other third parties they may have sold the list to. Needless to say virtually no list meets these criteria and as such the use of any purchased list is probably a no go.

Even if such a list was legitimate it's still a grey list the email address bounce rate can be anything up to 75% imagine paying for 100k emails only to find 75,000 don't actually exist anymore!

Purchasing or scraping emails is not the quick solution it appears to be, and could do you long term harm, not just to brand damage, but could see your legitimate emails baned from mail servers. The main reason not to do it is not legal or ethical it simply doesn't make financial sense. Though I would hope you would have stopped at it's not ethical :)

Legally? Depends on jurisdiction as different areas have different rules about the acquisition of personal data and how they get distributed (note that even stackexchange requests you sign up for several different accounts then merge).

Ethically? Nope. Try from the start again knowing that you won't make the same mistakes that you made while acquiring the last batch. Best of luck!