I have problems as I can not send attachments

You will have to give us more information to work with in order for us to give you informed suggestions.

- What version of Thunderbird?

- What is your operating system?

- Who is your email provider?

- Is this an IMAP account or POP3?

- What, specifically, happens when you try to send an attachment? What error messages do you see? Please quote them precisely and in full. Screen shots would suffice.

- What Anti-Virus or other security software do you use, if any?

Version 155 Windows 11 Telstra.com IMAP When forwarding a email the error is. Login to server mail.bigpond.com with username neilaudet@bigpond.com failed. I disabled my Anti-Virus. No security software

I re-installed Thunderbird, which after the re-install twice, this has fixed the problem and now seems to be working very well. Thank you. I did have the latest version, by re-installing the latest which I did have has Thunderbird working well.

Telstra sometime ago decommissioned all of the Bigpond server and you are trying to log into out.

I suggest you access the outgoing server (SMTP) part of account settings and correct the outgoing server name to one supported by telstra for that address. According to their website https://www.telstra.com.au/support/email/imap-pop-smtp-mail-server-settings is smtp.telstra.com