==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version:     v0.9.9
- Deployed with downloadable installer.
- Linux/BSD distribution name and version: CentOS Linux release 7.7.1908
- Store mail accounts in which backend (PGSQL):
- Web server (Apache or Nginx):NGINX
- Manage mail accounts with iRedAdmin-Pro? no, IRed Admin
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====
I have server x.domain.com that is my email server.  Then I have server y.domain.com that wants to send an email.  sent on the linux box by user dude

When I send the mail I get the following errror.  The email works to godaddy, but fails to att.com

I am thinking that I need to have dude@y.domain.com translated to dude@domain.com.

Thoughts?  Below is the contents for /var/log/maillog

Jan  6 17:52:29 x.domain.com1 postfix/postscreen[12680]: CONNECT from [192.168.1.76]:56770 to [192.168.1.83]:25
Jan  6 17:52:29 x.domain.com1 postfix/postscreen[12680]: WHITELISTED [192.168.1.76]:56770
Jan  6 17:52:29 x.domain.com1 postfix/smtpd[12681]: connect from y.domain.com[192.168.1.76]
Jan  6 17:52:30 x.domain.com1 postfix/smtpd[12681]: 47s9kk00P6z650: client=y.domain.com[192.168.1.76]
Jan  6 17:52:30 x.domain.com1 postfix/cleanup[12689]: 47s9kk00P6z650: message-id=<20200106225229.C3CF28B109@y.domain.com>
Jan  6 17:52:30 x.domain.com1 postfix/qmgr[1819]: 47s9kk00P6z650: from=<dude@y.domain.com>, size=2366, nrcpt=1 (queue active)
Jan  6 17:52:30 x.domain.com1 postfix/smtpd[12681]: disconnect from y.domain.com[192.168.1.76]
Jan  6 17:52:30 x.domain.com1 postfix/10025/smtpd[12698]: connect from localhost[127.0.0.1]
Jan  6 17:52:30 x.domain.com1 postfix/10025/smtpd[12698]: 47s9kk34mRz656: client=localhost[127.0.0.1]
Jan  6 17:52:30 x.domain.com1 postfix/cleanup[12689]: 47s9kk34mRz656: message-id=<20200106225229.C3CF28B109@y.domain.com>
Jan  6 17:52:30 x.domain.com1 postfix/10025/smtpd[12698]: disconnect from localhost[127.0.0.1]
Jan  6 17:52:30 x.domain.com1 postfix/qmgr[1819]: 47s9kk34mRz656: from=<dude@y.domain.com>, size=2891, nrcpt=1 (queue active)
Jan  6 17:52:30 x.domain.com1 amavis[17285]: (17285-05) Passed CLEAN {RelayedInbound}, [192.168.1.76]:56770 <dude@y.domain.com> -> <somebody@att.net>, Queue-ID: 47s9kk00P6z650, Message-ID: <20200106225229.C3CF28B109@y.domain.com>, mail_id: RkBtHJkEQjLV, Hits: -0.087, size: 2361, queued_as: 47s9kk34mRz656, 388 ms, Tests: [ALL_TRUSTED=-1,HDRS_LCASE_IMGONLY=0.1,HTML_FONT_LOW_CONTRAST=0.001,HTML_IMAGE_ONLY_20=0.7,HTML_MESSAGE=0.001,MIME_HTML_ONLY=0.1,T_REMOTE_IMAGE=0.01,URIBL_BLOCKED=0.001]
Jan  6 17:52:30 x.domain.com1 amavis[17285]: (17285-05) Passed CLEAN, <dude@y.domain.com> -> <somebody@att.net>, Hits: -0.087, tag=2, tag2=6.2, kill=6.9, queued_as: 47s9kk34mRz656, L/0/0/0
Jan  6 17:52:30 x.domain.com1 postfix/amavis/smtp[12694]: 47s9kk00P6z650: to=<somebody@att.net>, relay=127.0.0.1[127.0.0.1]:10024, delay=0.55, delays=0.14/0.01/0/0.39, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10025): 250 2.0.0 Ok: queued as 47s9kk34mRz656)
Jan  6 17:52:30 x.domain.com1 postfix/qmgr[1819]: 47s9kk00P6z650: removed
Jan  6 17:52:32 x.domain.com1 postfix/smtp[12661]: Untrusted TLS connection established to ff-ip4-mx-vip1.prodigy.net[144.160.159.21]:25: TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)
Jan  6 17:52:32 x.domain.com1 postfix/smtp[12661]: 47s9kk34mRz656: to=<somebody@att.net>, relay=ff-ip4-mx-vip1.prodigy.net[144.160.159.21]:25, delay=1.8, delays=0.01/0.01/1.7/0.08, dsn=5.1.8, status=bounced (host ff-ip4-mx-vip1.prodigy.net[144.160.159.21] said: 553 5.1.8 <dude@y.domain.com>... Domain of sender address dude@y.domain.com does not exist (in reply to MAIL FROM command))
Jan  6 17:52:32 x.domain.com1 postfix/cleanup[12689]: 47s9km2MfXz650: message-id=<47s9km2MfXz650@x.domain.com>
Jan  6 17:52:32 x.domain.com1 postfix/qmgr[1819]: 47s9km2MfXz650: from=<>, size=5227, nrcpt=1 (queue active)
Jan  6 17:52:32 x.domain.com1 postfix/bounce[12699]: 47s9kk34mRz656: sender non-delivery notification: 47s9km2MfXz650
Jan  6 17:52:32 x.domain.com1 postfix/qmgr[1819]: 47s9kk34mRz656: removed
Jan  6 17:52:32 x.domain.com1 postfix/smtp[12661]: connect to y.domain.com[192.168.1.76]:25: No route to host
Jan  6 17:52:32 x.domain.com1 postfix/smtp[12661]: 47s9km2MfXz650: to=<dude@y.domain.com>, relay=none, delay=0.02, delays=0.01/0.01/0/0, dsn=4.4.1, status=deferred (connect to y.domain.com[192.168.1.76]:25: No route to host)