Magento2: Magento 2.3: Password Reset Email not being sent: SMTPUTF8

[rauberdaniel]

Preconditions (*)

1. Magento 2.3.0
2. PHP 7.2
3. Postfix
4. Ubuntu 18.04.1

Steps to reproduce (*)

1. Configure Postfix to be able to send the Magento emails
2. Create a new user -> receive account creation mail on user address
3. "Forgot Password" in Magento, to try and reset the password

Expected result (*)

1. Email should be sent properly and customer should receive reset email on his address

Actual result (*)

1. Email cannot be sent because of missing SMTPUTF8 on SMTP relay (SMTPUTF8 is required, but was not offered by host)

Notes

This is not an issue of my relay or similar (I’m using Amazon Simple Email Service as a SMTP relay from postfix). It is configured properly and I can send emails using sendmail or from a PHP file with mail() without any issues. Also, none of the email addresses (neither customer address nor shop address) do contain any UTF8 characters, I even checked them with a hex reader. Other Magento emails like Account Creation send without any issues.

[magento-engcom-team]

Hi @rauberdaniel. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

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where $VERSION is version tags (starting from 2.2.0+) or develop branches (for example: 2.3-develop).
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@rauberdaniel do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• [ ] yes
• [ ] no

[magento-engcom-team]

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[ghost]

Hi @rauberdaniel thank you for you report, i'm not able to reproduce following steps you described,

[rauberdaniel]

@engcom-backlog-nazar Interesting. I just figured out that when I disable smtputf8 on the local postfix (it is enabled by default) the issue disappears. Apparently the local postfix tries to encode the mail as utf8 which then fails on the AWS SMTP server. I haven’t yet figured out why this only happens for some emails though. Thank you for your help and sorry for filing this issue.

For reference:
adding smtputf8_enable = no to /etc/postfix/main.cfg solved it (reference)

[ghost]

@rauberdaniel thanks, nice find.

[tdschmidl]

As we faced similar issues with a newly installed Debian stretch system and Magento 2.2.8, the culprit was - as far as I could debug - following:

Postfix on newer or freshly installed Debian (and derivates) systems sets following value in /etc/postfix/main.cf
Found this behavior on:
Postix version on Debian: 9.9: 3.1.12-0+deb9u1

• or -
  Postfix version on Ubuntu 18.04.1: 3.3.0-1ubuntu0.2

# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
# fresh installs.
compatibility_level = 2

As Postfix manpages explain (http://www.postfix.org/COMPATIBILITY_README.html#smtputf8_enable):

The smtputf8_enable default value has changed from "no" to "yes. With the new "yes" setting, the Postfix SMTP server rejects non-ASCII addresses from clients that don't request SMTPUTF8 support, after Postfix is updated from an older version.

Check if you are affected

run postconf -p | grep comp
it might result in:

user@host:~$ postconf -p | grep comp
backwards_bounce_logfile_compatibility = yes
**compatibility_level = 2**
enable_idna2003_compatibility = no
mynetworks_style = ${{$compatibility_level} < {2} ? {subnet} : {host}}
relay_domains = ${{$compatibility_level} < {2} ? {$mydestination} : {}}
**smtputf8_enable = ${{$compatibility_level} < {1} ? {no} : {yes}}**
sun_mailtool_compatibility = no

Workaround

Set smtputf8_enable = no on affected systems

Solution

Magento should encode non-ASCII addresses in Unicode (utf8 I guess)