lower case email address for delivery

[Juerg Reimann]

Dear list members,

Interesting phenomenon on a newly setup system:

2020-11-28T11:15:48+01:00 localhost postfix/lmtp[98782]: [ID 197553 mail.info] DDB5E8456: to=<[hidden email]>, relay=my.host.tld[private/dovecot-lmtp], delay=0.04, delays=0.02/0/0.01/0.01, dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]> User doesn't exist: [hidden email] (in reply to RCPT TO command))
2020-11-28T11:16:01+01:00 localhost postfix/lmtp[98782]: [ID 197553 mail.info] BF1678458: to=<[hidden email]>, relay= my.host.tld[private/dovecot-lmtp], delay=0.26, delays=0.25/0/0/0.01, dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]> User doesn't exist: [hidden email] (in reply to RCPT TO command))
2020-11-28T11:26:37+01:00 localhost postfix/lmtp[99560]: [ID 197553 mail.info] BA35E88DC: to=<[hidden email]>, relay=my.host.tld[private/dovecot-lmtp], delay=0.16, delays=0.08/0/0/0.08, dsn=2.0.0, status=sent (250 2.0.0 <[hidden email]> YIesL90lwl+2hAEA0J78UA Saved)

How can I lowercase the complete email address in postfix before delivery? It happens like this in my case:

virtual_transport = lmtp:unix:private/dovecot-lmtp

Thanks,
Juerg

[John Fawcett]

On 28/11/2020 11:30, Juerg Reimann wrote:

> Dear list members,
>
> Interesting phenomenon on a newly setup system:
>
> 2020-11-28T11:15:48+01:00 localhost postfix/lmtp[98782]: [ID 197553 mail.info] DDB5E8456: to=<[hidden email]>, relay=my.host.tld[private/dovecot-lmtp], delay=0.04, delays=0.02/0/0.01/0.01, dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]> User doesn't exist: [hidden email] (in reply to RCPT TO command))
> 2020-11-28T11:16:01+01:00 localhost postfix/lmtp[98782]: [ID 197553 mail.info] BF1678458: to=<[hidden email]>, relay= my.host.tld[private/dovecot-lmtp], delay=0.26, delays=0.25/0/0/0.01, dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]> User doesn't exist: [hidden email] (in reply to RCPT TO command))
> 2020-11-28T11:26:37+01:00 localhost postfix/lmtp[99560]: [ID 197553 mail.info] BA35E88DC: to=<[hidden email]>, relay=my.host.tld[private/dovecot-lmtp], delay=0.16, delays=0.08/0/0/0.08, dsn=2.0.0, status=sent (250 2.0.0 <[hidden email]> YIesL90lwl+2hAEA0J78UA Saved)
>
> How can I lowercase the complete email address in postfix before delivery? It happens like this in my case:
>
> virtual_transport = lmtp:unix:private/dovecot-lmtp
>
> Thanks,
> Juerg
>

Juerg

There is no configuration parameter to lowercase email addresses in the
postfix lmtp client. You should be able to configure dovecot to accept
case insensitive email addresses. It should do that by default in recent
versions. I believe the parameter to look into is auth_username_format.

John

> On 28 Nov 2020, at 06:35, John Fawcett <[hidden email]> wrote:
>
> On 28/11/2020 11:30, Juerg Reimann wrote:
>> Dear list members,
>>
>> Interesting phenomenon on a newly setup system:
>>
>> 2020-11-28T11:15:48+01:00 localhost postfix/lmtp[98782]: [ID 197553 mail.info] DDB5E8456: to=<[hidden email]>, relay=my.host.tld[private/dovecot-lmtp], delay=0.04, delays=0.02/0/0.01/0.01, dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]> User doesn't exist: [hidden email] (in reply to RCPT TO command))
>> 2020-11-28T11:16:01+01:00 localhost postfix/lmtp[98782]: [ID 197553 mail.info] BF1678458: to=<[hidden email]>, relay= my.host.tld[private/dovecot-lmtp], delay=0.26, delays=0.25/0/0/0.01, dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]> User doesn't exist: [hidden email] (in reply to RCPT TO command))
>> 2020-11-28T11:26:37+01:00 localhost postfix/lmtp[99560]: [ID 197553 mail.info] BA35E88DC: to=<[hidden email]>, relay=my.host.tld[private/dovecot-lmtp], delay=0.16, delays=0.08/0/0/0.08, dsn=2.0.0, status=sent (250 2.0.0 <[hidden email]> YIesL90lwl+2hAEA0J78UA Saved)
>>
>> How can I lowercase the complete email address in postfix before delivery? It happens like this in my case:
>>
>> virtual_transport = lmtp:unix:private/dovecot-lmtp
>>
>> Thanks,
>> Juerg
>>
> Juerg
>
> There is no configuration parameter to lowercase email addresses in the
> postfix lmtp client. You should be able to configure dovecot to accept
> case insensitive email addresses. It should do that by default in recent
> versions. I believe the parameter to look into is auth_username_format.

Postfix folds usernames to lowercase and this cannot be changed *unless this has changed in the also couple of years?). Are you saying that LMTP in postfix behaves differently than local(8)?

Postfix lookups are not case sensitive, so USER will match user.

--
Strange things are afoot at the Circle K

[Viktor Dukhovni]

On Sat, Nov 28, 2020 at 03:04:38PM -0700, @lbutlr wrote:

> > There is no configuration parameter to lowercase email addresses in the
> > postfix lmtp client. You should be able to configure dovecot to accept
> > case insensitive email addresses. It should do that by default in recent
> > versions. I believe the parameter to look into is auth_username_format.
>
> Postfix folds usernames to lowercase and this cannot be changed
> *unless this has changed in the also couple of years?). Are you saying
> that LMTP in postfix behaves differently than local(8)?

Yes, downcasing of recipient addresses is a feature of the local(8)
delivery agent, and is generally not done elsewhere in Postfix.

Keys for table lookups in fixed-key (rather than key pattern such as
regexp, PCRE, ...) tables are folded to lower-case, but the results
are are used verbatim.

Keys are passed verbatim to pattern-based tables, but these default
to case-insensitive matching (use "/i" to disable in PCRE and regexp).

> Postfix lookups are not case sensitive, so USER will match user.

Actually, Postfix works hard to avoid case-folding, especially for
messages that transit the MTA and are not delivered locally.

--
    Viktor.

[Nikolai Lusan]

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Hash: SHA512

On Sat, 2020-11-28 at 11:30 +0100, Juerg Reimann wrote:

FWIW it looks like a dovecot/lda issue.

Traditionally SMTP systems forced everything to be lower case ... but
then people like Microsoft started making MTA's that where case
sensitive for the reciever part of the email address (at the time this
was not RFC complianat behaviour). A quick parsing of the current RFC's
shows that for the reciever part (i.e. before the "@" symbol) it's up
to the delivery agent how it handles case sensetivity, however the
domain part of the address shouldn't be case sensitive. I have always
run on the basis that all email addresses should be case insensetive,
and that the MTA/MDA should ignore the case of any characters in any
part of the address. In the case outlined below I would look more
closely at your dovecot configuration than your postfix configuration.
I have a similar setup, but addmittedly I haven't tried (or seen anyone
try) using anything upper case in the email addresses I'm serving.

But, yeah, according to the RFC's it's up to the MDA/LDA how it handle
character case sensetivity :)

> Interesting phenomenon on a newly setup system:
>
> 2020-11-28T11:15:48+01:00 localhost postfix/lmtp[98782]: [ID 197553
> mail.info] DDB5E8456: to=<[hidden email]>,
> relay=my.host.tld[private/dovecot-lmtp], delay=0.04,
> delays=0.02/0/0.01/0.01, dsn=5.1.1, status=bounced (host
> my.host.tld[private/dovecot-lmtp] said: 550 5.1.1 <[hidden email]>
> User doesn't exist: [hidden email] (in reply to RCPT TO command))
> 2020-11-28T11:16:01+01:00 localhost postfix/lmtp[98782]: [ID 197553
> mail.info] BF1678458: to=<[hidden email]>, relay=
> my.host.tld[private/dovecot-lmtp], delay=0.26, delays=0.25/0/0/0.01,
> dsn=5.1.1, status=bounced (host my.host.tld[private/dovecot-lmtp]
> said: 550 5.1.1 <[hidden email]> User doesn't exist:
> [hidden email] (in reply to RCPT TO command))
> 2020-11-28T11:26:37+01:00 localhost postfix/lmtp[99560]: [ID 197553
> mail.info] BA35E88DC: to=<[hidden email]>,
> relay=my.host.tld[private/dovecot-lmtp], delay=0.16,
> delays=0.08/0/0/0.08, dsn=2.0.0, status=sent (250 2.0.0
> <[hidden email]> YIesL90lwl+2hAEA0J78UA Saved)
>
> How can I lowercase the complete email address in postfix before
> delivery? It happens like this in my case:
>
> virtual_transport = lmtp:unix:private/dovecot-lmtp

When in doubt RTR [Read The RFC] :)

- --
Nikolai Lusan <[hidden email]>
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[Michael Ströder]

On 11/29/20 3:48 PM, Nikolai Lusan wrote:
> Traditionally SMTP systems forced everything to be lower case ... but
> then people like Microsoft started making MTA's that where case
> sensitive for the reciever part of the email address (at the time this
> was not RFC complianat behaviour).

IIRC the local part of e-mail address was always defined as case-sensitive.

BTW: In old Internet mail systems the local part was often the Unix user
name. And according to POSIX standard this is case-sensitive (which most
people also forget).

Ciao, Michael.

[Bill Cole-3]

On 29 Nov 2020, at 9:48, Nikolai Lusan wrote:

> Traditionally SMTP systems forced everything to be lower case

This is not true.

RFC821 and RFC822 (1982) both define the local part of email addresses
as including upper or lower case letters and optionally case-sensitive
with the sole exception of the required "postmaster" address, which
systems must treat as equivalent in any mix of cases. In both of those
RFCs, the examples used for email addresses typically used mixed-case
local parts.

--
Bill Cole
[hidden email] or [hidden email]
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire

[Andrew Sullivan]

On Mon, Nov 30, 2020 at 12:48:09AM +1000, Nikolai Lusan wrote:

>however the
>domain part of the address shouldn't be case sensitive.

This is only kind of true.

In the DNS, domain names match in a case-insensitive but case-preserving way, _only if_ you are talking about an ASCII letter (i.e. a-z using the US alphabet with no "decorations").  This is specified in STD 13 (RFCs 1034 and 1035).  All other octets in a domain name label match exactly only.

Note that with internationalized domain names in the mix, the issue is more complicated.  In the current specifications (IDNA2008), capital letters aren't allowed at all, and it would be an error to encounter one in a domain name slot (such as the domain part of an email address).  Bizarrely, this means that the domain names example.tld and EXAMPLE.TLD and even eXaMpLe.TlD are all equivalent, but éxample.tld is legal, éxample.TLD is legal, and ÉXAMPLE.TLD is an error.  (I'm aware that's not how you spell example in French, I'm just using it for illustration.)  I don't think that the above considered TLDs or EAI, so I don't expect it is relevant; I just mention it for completeness.

Best regards,

A

--
Andrew Sullivan
[hidden email]