# Unable to send mail, email receipt unaffected \[SOLVED\]

**URL:** <https://discourse.mailinabox.email/t/unable-to-send-mail-email-receipt-unaffected-solved/10390>\
**Category:** Maintenance\
**Created:** [April 26, 2023, 10:25pm UTC](https://discourse.mailinabox.email/t/unable-to-send-mail-email-receipt-unaffected-solved/10390 "2023-04-26T22:25:43Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![darond](https://discourse.mailinabox.email/letter_avatar_proxy/v4/letter/d/41988e/32.png) [@darond](https://discourse.mailinabox.email/u/darond)\
**Post date:** [April 26, 2023, 10:25pm UTC](https://discourse.mailinabox.email/t/unable-to-send-mail-email-receipt-unaffected-solved/10390/1 "2023-04-26T22:25:43Z")

</div>

I am unable to send email from my mailinabox (v61.1), likely occurring for some days. Error message accompanying the error:

```auto
Apr 26 22:13:18 box postfix/submission/smtpd[18577]: connect from unknown[mysourceaddress xx.xx.xx.xx]
Apr 26 22:13:18 box postfix/submission/smtpd[18577]: NOQUEUE: reject: RCPT from unknown[mysourceaddress xx.xx.xx.xx]: 550 5.1.1 <test-fxteytopn@srv1.mail-tester.com>: Recipient address rejected: srv1.mail-tester.com; from=<my@email.co.uk> to=<test-fxteytopn@srv1.mail-tester.com> proto=ESMTP helo=<smtpclient.apple>
Apr 26 22:13:18 box postfix/submission/smtpd[18577]: disconnect from unknown[mysourceaddress xx.xx.xx.xx] ehlo=2 starttls=1 auth=1 mail=1 rcpt=0/1 quit=1 commands=6/7

```

Issue:  
`NOQUEUE: reject: RCPT from.....550 5.1.1......Recipient address rejected: ....`

exists for all users when sending no matter what external recipient. Issue does not exist when sending to an email address configured on the same box.

System Status Checks all green ✅  
apt upgrade/updates all done ✅  
sudo mailinabox run numerous times and box restarted ✅

I have dug around in numerous system and error logs without anything obviously jumping out to me, other than errors/warnings which seem consistent with a normal install.

Any suggestions on possible routes of investigation? I’m at a loss to understand why it has stopped working.

---

<div class="post-metadata">

**Author:** ![darond](https://discourse.mailinabox.email/letter_avatar_proxy/v4/letter/d/41988e/32.png) [@darond](https://discourse.mailinabox.email/u/darond)\
**Post date:** [April 26, 2023, 11:35pm UTC](https://discourse.mailinabox.email/t/unable-to-send-mail-email-receipt-unaffected-solved/10390/2 "2023-04-26T23:35:30Z")

</div>

Identified two lines in postfix main.cf:

> ```auto
> default_transport = error
> relay_transport = error
> 
> ```

Commenting both out:

> ```auto
> #default_transport = error
> #relay_transport = error
> 
> ```

now allows email to be sent freely (and received).

Are these lines default entries in a virgin miab?

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<div class="post-metadata">

**Author:** ![darond](https://discourse.mailinabox.email/letter_avatar_proxy/v4/letter/d/41988e/32.png) [@darond](https://discourse.mailinabox.email/u/darond)\
**Post date:** [April 27, 2023, 12:00am UTC](https://discourse.mailinabox.email/t/unable-to-send-mail-email-receipt-unaffected-solved/10390/3 "2023-04-27T00:00:48Z")

</div>

> [@darond](#):
>
> Are these lines default entries in a virgin miab?

Having quickly spun up a virgin box I can confirm they are not.

I have also identified in this Stackoverflow post that having IPv6 enabled on a server can also cause a similar issue, although main.cf does not align to the below:

> Change  
> `inet_protocols= all`  
> to  
> `inet_protocols= ipv4`

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<div class="post-metadata">

**Author:** ![system](https://discourse.mailinabox.email/uploads/default/original/2X/4/4d0933d13c456b7e57f296aa6cc344525b6f0c70.png) [@system](https://discourse.mailinabox.email/u/system)\
**Post date:** [June 6, 2023, 12:00am UTC](https://discourse.mailinabox.email/t/unable-to-send-mail-email-receipt-unaffected-solved/10390/4 "2023-06-06T00:00:52Z")

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