Membership Sending "Welcome" Communication Repeatedly

For some reason, people (including me) receive the communication I set to mail the day they pay for a subscription over and over.

They receive it for the free subscription. I think this may have something to do with the fact that, even on indefinite subscriptions, we have to choose a time period. I've changed it from 1 day to 365 years, so hopefully that will resolve it, but I think it might be a good idea to remove the "period" option when someone has selected "Indefinite."