inline border-radius property does not apply inside generated email

Question

I pass the HTML markup into the SmtpClient object and send it:

 using (SmtpClient SMTP = new SmtpClient(Settings.SmtpServer))
                    {
                        using (MailMessage message = new MailMessage())
                        {                               
                            message.From = new MailAddress(Settings.EmailFromAddressUS);                              

                            message.To.Add(new MailAddress(orderInfo.ShippingInfo.Email, string.Format("{0} {1}", orderInfo.ShippingInfo.FirstName, orderInfo.ShippingInfo.LastName)));
                            message.Subject = subjectLine;
                            message.Body = emailBody;
                            message.IsBodyHtml = true;

                            SMTP.Send(message); 
                        }
                    }

Inside emailBody variable I have such mark up:

<a href="www.test.com" style="background-color: transparent;Margin:0;border:0 solid #46323c;border-radius:4px!important;border-collapse: separate;perspective: 1px; color:#46323c;display:inline-block;font-family:Helvetica,Arial,sans-serif;font-size:16px;font-weight:700;line-height:1.3;margin:0;padding:8px 16px 8px 16px;text-align:left;">Sign Up</a>

On the client's side (Outlook 2016) that's the html received:

<a href="www.test.com" style="border-radius:4px!important;perspective: 1px;display:inline-block"><b><span style="color:#46323C;border:solid #46323C 1.0pt;mso-border-alt:
          solid #46323C .25pt;padding:6.0pt;text-underline:none">Sign Up </span></b></a>

The border-radius property is not applied and the button is squared. If I save the email as html I will have a rounded button as it should be.

Answer 1

if it is outlook, it may not be passed, the following pass:-

border-left

border-right

border-top

border-bottom

border-left-color

border-left-width

border-left-style

border-right-color

border-right-width

border-right-style

border-top-color

border-top-width

border-top-style

border-bottom-color

border-bottom-width

border-bottom-style

border-radius is at the helms mercy of outlook, can you please confirm which client you need to pass? border-radius will not work on specific outlook versions, particularly when it comes to litmus version testing.