For the Samsung calendar, tap on the menu (3 dots on the upper right corner)/settings/Select Alert Type/Off
I hope that's it. I saw nothing in the settings about email. I get the exact same options (for alerts) if I go thru settings/sound/calendar/select alert type
If you decide to try Google Calendar (from the play store)...
OK, I think I can answer this one. I've been working with Google Calendar for the last week, setting it up so that the 12 or so people that schedule jobs with my husband can see what dates are free or busy and send job details for me to post.
Log into your gmail acct ONLINE.
Click on the apps icon (a square of squares in the upper right portion of the screen.\
Choose Calendar
On the left side of the screen you'll see a link to your calendar(s)
Click on the down arrow on the right of the calander name and choose "Edit Notifications"
You have a list of things to be notified about. You can check or uncheck them.
The only way I see to set up 30 minute notifications (with both calendars) is via your mobile device.
Hope you were able to get something out of all that
