Send email from my custom mailgun SMTP address

Question

Sorry if I have not understood something but (I believe) I have searched enough for this.

1. First things first: I have successfully set up my domain (mydomain.gr) which has been verified.
2. I have created a custom SMTP address ([e-mail]).
3. I have created a route which forwards everything sent at *@mydomain.gr to my personal Gmail address.
4. Test 1: If I send an email from an external address ([e-mail]) to [e-mail] it is forwarded to my personal Gmail. OK!
5. Test 2: If I send from [e-mail] to any external address ([e-mail]) I get the error Free accounts are for test purposes only. Please upgrade or add the address to authorized recipients in Account Settings. Of course the password is correct while sending. Otherwise another error is raised.

I think I have missunderstood some things...

So here comes my question:

How can I send email from my custom SMTP email address? (I do not wish to upgrade my account since this -free- Mailgun account will handle very small amount of emails. So, 10K are more than enough for me.)

Answer 1

OK. After some emails with the mailgun team I finally figure it out!

All I had to do was to upgrade my account (just enter credit card info). Now I can send email from [e-mail] to anyone.

Thank you mailgun!

Answer 2

I have also contacted Mailgun for the issue and get response back within few minutes:

This error occurs whenever utilizing either a sandbox domain or a free account without inviting users called Authorized Recipients.

Sandbox domains always require Authorized Recipients. With free plans, which are intended for test usage, all custom domains require Authorized Recipients. With upgraded plans, which are intended for production usage, custom domains no longer require Authorized Recipients.

Please take a look at the following Help Center article for more information about the Authorized Recipient process:

https://help.mailgun.com/hc/en-us/articles/217531258-Authorized-Recipients

Then I have add the Authorize Recipients and it works like a champ!