Obviously it results in higher open rates and more sales.
When someone signs up for your list.
In the welcome email you should welcome them and tell them again what they are going to receive from you via email.
Give them the benefits they will get from opening your emails.
Then tell them that they have to reply to your welcome email because you do not want them to lose out on all the goodies you are going to share with them.
If they reply to the email then your emails won't end up in their spam folder.
If enough people reply to your welcome emails then your email provider will see that as a good signal and send your emails to their inboxes. even works with Gmail.