Issue sending mails from myuser@mydomain.localdomain

I’m hoping someone can help me with this.

I have a problem with my Virtualmin email system that seems to want to use the format of


I’m pretty sure its an issue with the but am reluctant to start messing with it myself without a little help from this forum.

Appreciate any comments.

This is the extract of the section (I think) from the


The myhostname parameter specifies the internet hostname of this

mail system. The default is to use the fully-qualified domain name

from gethostname(). $myhostname is used as a default value for many

other configuration parameters.

#myhostname = host.domain.tld
#myhostname = virtual.domain.tld

The mydomain parameter specifies the local internet domain name.

The default is to use $myhostname minus the first component.

$mydomain is used as a default value for many other configuration


#mydomain = domain.tld

bearing in mind i host a few different domains, i wasn’t happy just changing anything.



Hmm, just to clarify – when are you seeing that issue?

Anytime something is sending an email from your server, it should set a “From” address. So the first thing you may want to do is verify that anything sending an email sets a “From” address when doing so.

However, as to why you see that behavior when a client isn’t setting a From address – you may want to double-check your server’s hostname, which you can do by running the “hostname” command.


Thanks Eric, this is the reply i got from attempting to send an email to someone.

host[] said: 553 #5.1.8
Domain of sender address steve@MyDonainName.localdomain does not exist (in reply
to MAIL FROM command)

MyDomainName was the original domain name and was just changed for privacy.
Its only seems to send from the localdomain when sending a mail from the system. If i send one from my mail client it sends just fine with the correct address.

My hostname is a mirror of the domain.


thanks for your time on this, really appreciated.

Just to be super-clear, you’re saying that if you run the command “hostname”, you’re seeing “”?


Thats Correct, do you think this is the issue? should i change the local machine to
is it adding the localdomain due to it being the same as the local tld?


There’s likely a reference to the incorrect name somewhere on your system.

What is the output of “postconf -n”?

Also, is the contents of your /etc/hosts file?


Thanks again for your time on this.

Hosts file (IP_removed with MYPUBLICIP) localhost.localdomain localhost localhost4.localdomain4 localhost4

Auto-generated hostname. Please do not remove this comment.

::1 localhost localhost.localdomain localhost6 localhost6.localdomain6


alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
allow_percent_hack = no
broken_sasl_auth_clients = yes
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5
home_mailbox = Maildir/
html_directory = no
inet_interfaces = all
inet_protocols = all
mail_owner = postfix
mailbox_command = /usr/bin/procmail-wrapper -o -a $DOMAIN -d $LOGNAME
mailbox_size_limit = 0
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
message_size_limit = 14800000
mydestination = $myhostname, localhost.$mydomain, localhost,
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES
sample_directory = /usr/share/doc/postfix-2.6.6/samples
sender_bcc_maps = hash:/etc/postfix/bcc
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
unknown_local_recipient_reject_code = 550
virtual_alias_maps = hash:/etc/postfix/virtual