Calibre won't send by email

[ukdangerous]

Hi All

Apologies' if already asked / answered elsewhere, I did a search and from scanning the titles of the subjects, could not see a suggested answer

Calibre version:5.12.0
Kindle for PC version: 1.30.0

just downloaded both kindle for pc and calibre (as recommended elsewhere).

I thought I had configured everything correctly in Calibre, but somehow when I send a test book (converted to mobi from epub) it does not appear on my kindle for pc application (I can download direct from Amazon fine though and it will appear on the pc app).

Calibre mail settings:
Hostname: mail.gmx.com
Port: 587
Username:aaa@gmx.com (where aaa = the email address I created e.g. tom@gmx.com)
Password: - the password used to access the gmx email account
Encryption: TLS

I have set my gmx email as the default email (and made sure it is registered on the amazon account) and sending a test email works fine.

The issue seems to occur at the latter end of the process unfortunately, when I right click the book (already in MOBI format) and choose Connect / Share and then email to xxxx@kindle.com (where xxxx is the username that kindle assigned me)
) it doesn't go through and I get a message in my gmx account that

"Your message to xxxx@kindle.com, sent at 03:44 PM on Sat, Mar 06, 2021 GMT did not include any attached documents or image files"

I have re-run the welcome wizard again located in the drop-down option on preferences) to no avail.

Any ideas on what I am doing wrong (with suggestions to how to remedy it)?

Any other answers that I have missed please ask and I will provide them, as I getting getting increasingly frustrated with an otherwise incredible piece of software (Calibre).

TIA

ukd

[PeterT]

Try downgrading calibre to 5.11.