So I switched to Outlook before seeing these messages.
Tried sending a book, which took ages, then I got this error message . .
Starting job: Email The Last Bookshop in London to
magsps_WoEg0Q@kindle.com
connect: to ('smtp-mail.outlook.com', 587) None
reply: b'220 LO4P123CA0349.outlook.office365.com Microsoft ESMTP MAIL Service ready at Mon, 4 Sep 2023 08:43:43 +0000\r\n'
reply: retcode (220); Msg: b'LO4P123CA0349.outlook.office365.com Microsoft ESMTP MAIL Service ready at Mon, 4 Sep 2023 08:43:43 +0000'
connect: b'LO4P123CA0349.outlook.office365.com Microsoft ESMTP MAIL Service ready at Mon, 4 Sep 2023 08:43:43 +0000'
send: 'ehlo [192.168.0.117]\r\n'
reply: b'250-LO4P123CA0349.outlook.office365.com Hello [92.40.33.128]\r\n'
reply: b'250-SIZE 157286400\r\n'
reply: b'250-PIPELINING\r\n'
reply: b'250-DSN\r\n'
reply: b'250-ENHANCEDSTATUSCODES\r\n'
reply: b'250-STARTTLS\r\n'
reply: b'250-8BITMIME\r\n'
reply: b'250 SMTPUTF8\r\n'
reply: retcode (250); Msg: b'LO4P123CA0349.outlook.office365.com Hello [92.40.33.128]\nSIZE 157286400\nPIPELINING\nDSN\nENHANCEDSTATUSCODES\nS TARTTLS\n8BITMIME\nSMTPUTF8'
send: 'STARTTLS\r\n'
reply: b'220 2.0.0 SMTP server ready\r\n'
reply: retcode (220); Msg: b'2.0.0 SMTP server ready'
send: 'ehlo [192.168.0.117]\r\n'
reply: b'451 4.7.0 Timeout waiting for client input [LO4P123CA0349.GBRP123.PROD.OUTLOOK.COM 2023-09-04T08:48:46.273Z 08DBAC98AF58F227]\r\n'
reply: retcode (451); Msg: b'4.7.0 Timeout waiting for client input [LO4P123CA0349.GBRP123.PROD.OUTLOOK.COM 2023-09-04T08:48:46.273Z 08DBAC98AF58F227]'
Sending failed...
Any further advice please?