Sendgrid not delivered!

Every time a user logs in to my application form, an email is sent to the application to confirm the registration, but if the email entered in the form is Hotmail / Outlook it will not receive this confirmation, this is occurring because microsoft blocks all submissions done by sendgrid ... I have not found the solution to this and I wonder if there is another tool that can replace sendgrid in asp net mvc? This is because I will not be able to use the standard SMTP method normally used ... I know this question is not appropriate, so in my internet search I did not find any relevant help. If anyone can help me, I'll be grateful!