app/mailers/comment_mailer.rb
class CommentMailer < ActionMailer::Base
default from: "comments@writeverba.com"
def send_comment_mail(comment_user, comment)
@comment_user = comment_user
@comment = comment
@post = Post.find(@comment.post_id)
@post_url = post_url(@post)
mail(to: @post.user.email, subject: comment_user.username + " commented on your post")
end
end