Seeing it on your PC
A mail app such as Outlook or Thunderbird connecting out to 995 (or 110) is collecting mail.
Should you block it?
Outgoing is fine for a mail app. Prefer 995: on 110 the password may cross the network in plain text.
Check it on your PC
Run this in PowerShell to see what is using port 110 right now, and which program owns it:
Get-NetTCPConnection -LocalPort 110 -ErrorAction SilentlyContinue | Select-Object LocalAddress,LocalPort,RemoteAddress,RemotePort,State,@{n='Process';e={(Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue).ProcessName}}No output means nothing is using the port at the moment. For every connection at once, paste netstat -ano into the netstat explainer.
Block it in Windows Firewall
In PowerShell run as administrator, this stops other computers from connecting to this port on your PC. It does not stop your own programs connecting out.
New-NetFirewallRule -DisplayName "Block inbound TCP 110,995" -Direction Inbound -Protocol TCP -LocalPort 110,995 -Action Block
Undo it with Remove-NetFirewallRule -DisplayName "Block inbound …", using the same name. If you depend on the service on your local network, this rule stops that too.