E-Newsletter. Cannot send emails!

Hi there,

I am almost loosing my mind. I cannot figure out how to configure the outgoing email settings correctly on one specific domain. I actually tried to set it up with Mandrill but not even without it is working. Here is what I tried so far.

1. I have read these topics and tried to apply the suggestions:
https://premium.wpmudev.org/forums/topic/setting-up-enewsletter-with-mandrill
https://premium.wpmudev.org/forums/topic/how-do-i-set-up-the-e-newsletter-with-mandrillcom-email-service
https://premium.wpmudev.org/forums/topic/with-e-newsletter-and-mandrill-smtp-or-api

2. I have tripple checked all entered details.

3. I have installed the WP Mandrill plugin. All standard emails, such as user registration are working. Also emails send from other plugins.

3. Here are the errors I get with different settings.

1. SMTP (with Mandrill details) and Mandrill Plugin activated: After testing the connection this is coming up: "Error details: The following From address failed: *****@*****.com : Called Mail() without being connected"

2. SMTP (with Mandrill details) and Mandrill Plugin deactivated: "SMTP server error: Relaying is administratively denied"

3. SMTP (Local SMTP settings not Mandrill) and Mandrill Plugin deactivated: "Failed to send test email! - Please check your outgoing email settings and server config to see if selected ports are open. Error details: The following From address failed: *****@*****.com : Called Mail() without being connected"

4. PHP Mail (same email address as in general settings): Trying to send a test email results in this: "Failed to send test email! Please check your outgoing email settings."

I already contacted the hosting provider (Bluehost) and they say all their smtp ports are open. I really would like someone of you having a look in the settings as I really do not know what else to do. However, as this is a client website, we were not allowed to install the WPMU dashboard, but I could send you the login details any time.

Thank you so much.

Best

Jan