Re: suggestions for altering outbound SMTP to work-around multi-CC denials

On Thu, 19 Feb 2026, [email protected] wrote:

> I'm already using postfix for things like routing outbound email to
> different proxies based on the sender domain, and maybe this task
> could be done from filters called by postix.
>
> Ideas, and has anyone else started seeing this problem (enterprise SMTP servers refusing to accept mail that references multiple
> recipients in message body)?

This is not my primary use case - need to check if this breaks - the only thing I needed to improve gmail was this ruleset
in my sendmail configuration, that creates a separate slow queue for them:

LOCAL_RULESETS
Squeuegroup
R$*                             $: $>canonify $1
R$* < @ gmail . com . >         $#gmail
R$* < @ googlemail . com . >    $#gmail
LOCAL_CONFIG
Qgmail, P=/var/spool/mqueue/googlequeue/gmail.com, I=30m, J=4, r=5, R=1

Marcin