After add alias Sender address rejected

hello I have successfully created a relay ( that works great as synonymous.
I use a main email ( to get in all the alerts, infos etc. Now I have an alias for to forward the mails to
Unfortunately that did not work out. the following error message comes from the mail system: Sender address rejected: not owned by user

is the problem with postfix?

here the from the relay.

# See /usr/share/postfix/ for a commented, more complete version

# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
#biff = no

# appending .domain is the MUA's job.
#append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

#readme_directory = no

# See -- default to 2 on
# fresh installs.
compatibility_level = 2

# TLS parameters
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname =
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
relayhost = []:587
mynetworks = [::1]/128 [fe80::]/64
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = loopback-only
inet_protocols = ipv4

mydestination =
smtp_tls_security_level = verify
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/relay_password
smtp_sasl_tls_security_options =
sender_canonical_maps = hash:/etc/postfix/sender-canonical

The alias HAS to point to the senders ORIGINAL email in order to allow this.

Thanks for your Answer.

i go to MIAB-Control Panel > Mail > Aliases

and entry this

Forwards To:
and check Any mail user listed in the Forwards To box can send mail claiming to be from the alias address.

as far as right?

webmaster should now be able to send mail as info.

I would like the webmaster to receive emails from info.

but it does not work, because the upper error message comes.

Do you have any idea where is the problem?

does not anyone have an idea?

webmaster (wait wrong one … was thinking of hostmaster) IS an alias … so it cannot be used.

webmaster is the admin of MIAB. My goal is it all new email users that I put in MIAB should be routed the emails of it on webmaster, so that I have to use an email (webmaster) at the end instead of adding a new email account to my email program. I hope you can understand what I mean.

@sakis2018 Translation - please correct me if I am wrong…

You want ALL emails to be delivered to the ‘webmaster’ mailbox, so that you can reply to them from ONE account on a email client such as Thunderbird on your PC (phone, tablet, whatever) - correct?
However, when you reply to those emails you want the reply to appear to be sent from, not - correct?

Yes, that’s exactly what I want.

OK … so what did you mean by …

Did you mean that you had created the ALIAS (rather than relay)?

and is this post in any way related to your post about setting up a mail relay on another server?

Ok here what I’ve done so far.

After creating a new user in the MIAB, I created a relay on the other server (running a forum) using this tutorial Mail-in-a-Box Advanced Configuration Guide. so far everything has worked. Now I want to redirect all emails to webmasters, as they already described above.

and is this post in any way related to your post about setting up a mail relay on another server?

Yes it is, but I have already solved this problem.

So the relay on the other server which is running a forum is set up for which purpose exactly?

I will assume that it is relaying OUTGOING email from the forum software to the MiaB for delivery to the internet, is that correct?

Please bear with me, I am trying to paint as complete of a picture as possible. :slight_smile:

Yes that’s right so far.

Was this line in your original MiaB configuration, or did you add it … or is this on the install of Postfilx on the ‘forum server’?

This is in the Postfix on the forum server.

Ok, so to confirm you have made NO changes to the Postfix config files on the miab server?

I am not convinced that the change you made on the forum server was necessary/wanted … but let’s leave that alone for the moment. I need to do some reading, be back shortly.

That’s correct, I have not changed anything to the postfix of MIAB.

Thank you for your effort.

@sakis2018 Which email address or addresses are emails from the forum being sent as?

In other words, what is the from: address?

Are the all being sent as or are there other addresses being used?

Another question … which client are you using to send the emails that you are getting this error? Is it the forum software, or Roundcube? or something else?