Testmail 

to test a person's email address by sending a message to it with the subject line reading "test mail". It means to repsond to it as soon as possible to ensure that the owner of the email address received it

For example, Chuck gives Boots an email address over the phone and sends him a "testmail." Boot receives it and lets Chuck know of it over the phone or by responding to it

Testmail by jeffersonson November 30, 2018

textmail 

Sending an email to someones phone. So they have a text.

Hey you don't have a cell phone send me a textmail from your email account.

textmail by yeahigotit July 2, 2009