Sent from my comcast email, blocked as spam with URL link

I sent an email from my comcast email to a hotmail address, it was cancelled and returned with the following reason 'Your message was not delivered to its intended recipient(s) because our automated spam filtering tools recognized one or more characteristics of your message as potentially associated with spam.' The only thing I could find that may have triggered this in the email was a web URL link for a car forum ending in .com. If I send an email with any web link in it will it be flagged as possible spam, so no links can be sent? Is there a way to verify a safe link? 

Thanks