Problem with Microsoft E-Mail Accounts (inbox) - any solution?

[Scandal]

Hello all!
I have a vB3.8 forum with 11.000 members.
My problem is that an amount of 4500 members have hotmail.com/hotmail.gr/live.com/windowslive.com e-mails and Microsoft has blocked our server IP/ or maybe the postman@mydomain.com e-mail. So, for 4500 members, no e-mails can send to their inbox (thread subscriptions/pm receive notification/change password/activate account via e-mail etc).

My question is: what could I do for this?
Is there any service for free or paid, to integrate my vBulletin 3.8 with it and send the e-mails with no problems?

1-2 times per year, I send mass e-mails to my members (as I notice above, currently I have 11.000 members).

I see [vBtise] MailChimp vBulletin Integration
but I'm not sure that it is what I need. Is it?

Any ideas are welcome!!

[Dave]

sendgrid.com, mailgun.com, mandrill.com, critsend.com

[Scandal]

Could you describe a bit, how they work?

I need to replace my vB3's PHP e-mail sender, with a new e-mail post service. Just need the same results (= vBulletin can send e-mails to all e-mail accounts/providers), but the e-mails to be sent on Microsoft Accounts too ('cause Microsoft has block my IP, as for lots other Forums).

[Dave]

You create an account at one of those services, get your information verified, create the right DNS records at your domain name and then they will give you the SMTP IP/username/password which you can use at the SMTP settings of vBulletin.

[RichieBoy67]

I have been through this.

You need to first fix your dns using http://mxtoolbox.com/. Use the domain health tool. You need an spf txt and make sure your soa timing is correct.

Then find the Microsoft email policies and make sure you have them all for the form you need to fill out to have your address unblocked.

I cannot do it this weekend but next week if you need I will find the information. Microsoft was actually very helpful but you will need to do some work on your end. You will need a privacy statement, unsubscribe links, opt in link, etc.