emails

I have some emails on my mailing list that are from 2016 and I was wondering if I should keep them or delete them after some time. My email list is really small right now so I was thinking I should keep them but I don't know if that is a good practice or not.

I was wondering what some thoughts were on sending thank you emails to people that subscribe to your email list. What do you think about doing this?

I was wondering if it is a good idea to send out friendly emails to my emails list. Things like happy holiday type emails, thank you for being on my mailing list and things like that. Is that a good idea or should I keep things strictly professional and business oriented?