Sending via SMTP when not on Xfinity Network

Begining last week I am no longer able to send email when connected to a non-xfinity network.  It does work from my phone when connected via Verizon Cellular, but as soon as I connected to WiFi sending email was blocked.  Has Comcast made a change to the security settings on the email server for SMTP?  This is a real pain when travelling.

Thanks,

Dave