Blocking akamaiedge.net

So after months of testing and using pi-hole I could never find what a few active uses were.

e673.dsce9.akamaiedge.net

it turns out to be related to the website GMX.com and email.

using the follow caused problems

(\.|^)akamaiedge\.net$

however i blocked the follow

e673.dsce9.akamaiedge.net
e11108.b.akamaiedge.net
e6858.dsce9.akamaiedge.net

now are they related to gmx.com email ?????