ETC is said to stand for "End of Thinking Capacity". Etc is used when you run out of words to explain or write series of things.
I have been learning about Neutron Stars, Dwarf Stars, Supernova, Hypernova, Black Holes Etc. Etc.
邮件由 firstname.lastname@example.org 发出。我们决不会发送垃圾邮件。