Hi Kenneth,
Thank you for your interest in Syncfusion products.
I am afraid that I was not able to reproduce the problem. I created a simple sample and it displays the text "@1234" without mailto link. I had placed the sample along with the output PDF in the link below. Please run it and send us the modified sample if you still see the problem.
Regards
Geetha
TextInPDF_4b2067aa.zip