How to use as a smtp server for multiple emails?

I have a few email address scattered around and have been using Comcast as a mta but they’ve gotten snotty and won’t help with an error message. They tell me it’s my configuration and to contact Thunderbird for help. So I decided to try MIAB. It works fine when the email is being sent from the address I configured it for but fails when I try to use it to send email from another email.
“An error occurred while sending mail. The mail server responded:
5.7.1 Sender address rejected: not owned by user
Please check the message recipient "” and try again"

Is there a way I can configure it to accept other email addresses?


MailInABox only allows emails to be SENT from authenticated users, and only the user’s email + any aliases created for them to send.

Are you trying to consolidate your emails?

if you are, might I recommend:

  1. A VPS provider of your choice (Be mindful of their ToS)
  2. Load ubuntu 14.04 + MIAB.
  3. Forward ALL emails from each other account, to an account on your MIAB server using:
    c. etc

The above (a,b,c) allow you to easily configure rules in the web mail client to move incoming email from each mail box into a folder of your choice. Also note: the “gmail+” is a tag, no need for more than one account just prepend “string+” to an email address hosted on MIAB to get it in that mailbox, but create a rule first to move that email to a specific folder. I hope this helps!


Your email could be
Forwarded GMail tag could be
Make a rule in roundcube to move any email with the tag “gmail” or to email "" to the folder in roundcube called “Gmail”

Good information, however it doesn’t address my problem. I’ve been using Comcast as an smtp server and they changed something and it doesn’t work any longer and refuse to help me. I used my comcast user/pw to log in, so I wasn’t using it as an open relay.

The address that I’m trying to send from is an alias at gets forwarded to one of my email addresses from a server at ARRL. I’m simply trying to find a way to create emails with a from: I have MIAB running on a VPS and working well for sending receiving emails for that domain. I’m a bit confused over the terminology in the “mail/alias” page. It seems to imply that if I have an alias that forwards to another email address, if I have the right selection, “ny mail user listed in the Fowards To box can send mail claiming to be from the alias address.” then the email that I’m aliased to can send email, but that doesn’t seem to be the case. The column “Permitted Senders” is blank for forwards to where is a valid email on my domain. Of course when I attempt to use MIAB I still get the “An error occurred while sending mail. The mail server responded:
5.7.1 Sender address rejected: not owned by user”

In the list of domains and ailiass I see
Alias Forwards to Permitted senders


You don’t need comcast as an SMTP Relay as long as you avoid port 25…

I’m not using port 25. I need a smtp relay of some kind and MIAB isn’t working. I’m no longer trying to use Comcast, I was trying to use my MIAB box but it won’t accept mail to be forwarded from Please read my previous post.

Here’s how the config looks


does it accept mail from else where? Because what you are describing is MIAB works, but cannot accept mail from a particular domain, which could be either:

A) MIAB is blocking that domain because it is blacklisted somewhere (Either in MIAB or spamhause,etc)
B) The server “” is not allowing forwarding of email?

I wouldn’t be able to help further without looking at the server logs themselves. Sorry!

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