I have always previously use this, but for some reason now in Google I can't add a custom email address and send the email's via googles servers.This is badThe old screen looked like this: this screen used to show this:Have google removed this fantastic feature? How can i enable this feature again?
How to add On behalf of in Gmail
google chrome;email;gmail
I just set this up a few minutes ago to send mail from my primary (personal) Gmail account as my secondary email address (an academic email) that uses Google Apps (e.g. youremail@googleappsdomain.com)Just make sure you enter the following information during setup:SMTP server : smtp.gmail.comUsername    : youremail@googleappsdomain.comPort        : 587 (enable TLS)Password    : enter your Google Apps email passwordIf you get an error message that looks like this:Authentication failed. Please check your username/password.[Server response: 535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8 http://support.google.com/mail/bin/answer.py?answer=14257 p10sm4562279obk.2 - gsmtp code(535) ]That probably means that you have 2-Step Verification enabled. If so, make an app password and use that auto generated password instead of your Google Apps email password.