I am emailing my sisters from my Comcast email address - My sister has a @Frontier.com email address. My other sister is @Me.com. The @Me.com receives my emails just fine but the @Frontier.com email does not show in her inbox.
I am able to receive emails from her, and when I reply, she never receives it.
Thank you for your help!
Tell her to check her spam folder. But if it's not that, she needs to contact Frontier and see if there is a blocking issue for your email address or the Comcast domain.