In the mac mail app, it is possible to select the from-email in the dropdown menu.
The available from-email adresses correspond to the added acounts.
Adding accounts on a mac:
In Yosemite: System Preferences -> Internet Accounts -> +
In Snow Leopard: Mail app -> Accounts -> +
To add an account, you need the email-address and the password.
Adding accounts to a private gmail:
www.gmail.com -> Settings -> Accounts and import -> Send mail as: -> Add another email address that you own
Here no password is required – You just have to reply to a confirmation email.
I want to be able to write from a Google-group-email on my mac. The problem is that there is no password for this email. (It is not an account, that you can log into).
How can I add this email/account to my mac? -or solve the problem in an other way? -so that I can write from the mac mail app, and not just my private gmail webmail.
Additional informations about the Google-group-email:
I am the administrator of a Google Apps for Education domain. I am the owner of the group in this domain. The group has three members. The group has an email-address: my_example_group@my_example_domain.com. It is not possible to log into into this account. The emails send to the address is automatically forwarded to the three members.
Best Answer
As long as you are an "Owner" of said Google Group, you can just add the email as an "Alias" in the Mail.app.
Simply add the email address of the owned Google Group. In your example "mysecond@email.com".