elasticemail.comは安全ですか？

Elastic Email is not the originator of the emails, it is an Email Service Provider. However it is an Email Service Provider that reacts very slowly if at all to complaints, and therefore it ends up being a Spam Service Provider. Email Service Providers are needed because most folks do not have the capability to set up their own facilities for sending legitimate bulk email and there is a genuine need to do it as a service. However there is the potential of having such a service abused for spamming, which is why any ESP must require their customers to abide by a watertight Acceptable Use Policy forbidding all involvement with spamming and enforce it carefully and swiftly. Otherwise you end up here.