When emailing a contact via the HL UI, the FROM email address should always default to the email address specified in that account's Setting > Email Services configuration. Failing to do so is irrational, as defaulting to sending FROM the email address assigned to the currently logged-in user means SMTP authentication will fail, except in rare instances where it just so happens the currently logged-in user has the exact same email address as the one specified in Settings > Email Services. This is particularly egregious when one has an Agency with many subaccounts, all of whom are for different users. Example: Say my name is Bob Smith, email bob@smith.com, and I log into my account as an Agency admin. I have subaccounts for different staff members: Jim Johnson, jim@johnson.com, and Kevin Nations, kevin@nations.com. Each one of these users wants to communicate with their contacts using their own email address, so SMTP auth for each account is of course set up to use their respective email address (and, of course, their address will be used 95% of the time, since they will be the ones using the account). Because HL is configured illogically in-regards contact email FROM settings, every time I go to a specific subaccount, and attempt to send a contact an email, HL defaults to sending from bob@smith.com, my email, instead of jim@johnson.com, the email configured in Settings > Email Services.. So every single email I send to a contact on Jim Johnson's account, I have to edit the FROM field every single time. And every other user has to do the exact same thing any time they access any other subaccount that isn't their own.