What mailing list service can I add emails to, without opt-in?

You should be able to import your current subscribers from Excel into most email marketing services without requiring them to opt-in again. In case you’re considering disabling the double opt-in feature (which I don’t recommend because it could increase your odds of being marked as spam), there are some services that allow you to disable double opt-in, including Benchmark Email. A few other services, like StreamSend, do not even offer a double opt-in feature. If you have the free MailChimp account, double opt-in cannot be disabled. Source: http://www.email-marketing-options.com/

You can batch import emails into Mailchimp for sure; the onus is on you to make sure the list is opt-in. If you start to get a lot of complaints or unsubscribes, they reserve the right to suspend or cancel your account. That being said, you can import a csv or excel (I think, haven't done it in a bit) easily however. These people will be 'subscribed' and will not receive any welcome emails or anything like that.

Mailchimp doesn't require opt-in, same goes for its integration with https://www.ladesk.com/#support

Easy. Directly import the .csv file of your subscribers into MailChimp. Just know that MailChimp will most likely ask you how your subscribers opted in, so ... Remember to export the FULL data from your website table which will hopefully include the IP address of each subscriber when they opted-in. This is your opt-in 'proof' should MailChimp ever ask for it. Hope that helps. Best, Frank

I was just digging around and found the following Mail Chimp API which appears to let you avoid the opt-in process. http://goo.gl/KXPu1

Our service, jMailerPro allows you to manage your email marketing however you want. You're welcome to upload any lists you like.

I wouldn't use MailChimp or Aweber. They only allow their clients to send to opted-in email addresses. Clickback has designed an email-sending platform that allows you to utilize your cold business contacts (i.e. you can connect with the people who've provided you with their business cards). It's the only software out on the market that can handle this type of sending. Here's the website http://www.clickback.ca - there's a live chat tool you can use to speak with Clickback email experts if you have any questions.

I have imported lists into mailchimp before over 6000 people and they flagged my account and made me send them the paperwork or webform confirmation in which the users opted in by checking a box somewhere. If you cannot provide that proof, they will make you send out an opt-in email first. To my knowledge, all email services do this if your list is large enough.

I represent AWeber. We do allow you to https://help.aweber.com/hc/en-us/articles/204405938-How-Do-I-Import-Subscribers-Without-Confirmation-. Let me know if you have any questions... happy to help.