[Users] [Bug 4601] New: gmail no longer supports "insecure" client

[Michael Schwendt]

On Mon, 20 Jun 2022 14:06:24 +0100, Abrolag wrote:

> I've attached an entire (returned) test message - including all headers.
> If someone here can make sense of it I'd be very grateful.

The error description is clear about why your message was rejected,
and none of it is related to using Claws Mail as MUA:

    host gmail-smtp-in.l.google.com [74.125.140.27]
    SMTP error from remote mail server after end of data:
    550-5.7.26 This message does not have authentication information or fails to
    550-5.7.26 pass authentication checks (SPF or DKIM). To best protect our users
    550-5.7.26 from spam, the message has been blocked. Please visit
    550-5.7.26  https://support.google.com/mail/answer/81126#authentication for more
    550 5.7.26 information. 4-20020a056000154400b00219af0c48cbsi18921899wry.732 - gsmtp