Sign in after using "Mailing group" from the main menu and select "Delivery Options". Now you can
change your subscription option as followed:
you'll get every mail individually (standard option).
many mails are merged daily into just one mail.
no mails will be delivered, but can still be viewed online in the message archive where only members have access. This option can also be used for temporary unsubscription (maybe during a birding trip etc.). And if you like to use more than one email address to post to EuroTwitch but don't want to receive mails at every account, this option will work perfect.