That will be an issue on the receiving end. What folks simply do not understand is email has no guarantee of delivery, any more than it's paper based predecessor.

With this absence of a delivery guarantee, many providers simply drop mail their spam filters think is spam. So really your only option is to send plain text email to those people in the hopes your mail gets delivered with a greater level of reliability. or contact both your provider and the recipients provider in the hopes they can work out why your mail goes missing.

Thanks for the reply. You mean there is another sort of e-mail besides plain vanilla ASCII ?  :-)

The annoying thing is that for reasons far too complicated to go into I also run The Bat on a VM on the same Ubuntu box using exactly the same settings & mail to this supplier always goes through from The Bat. (and has done for about 8 years. The problem has arisen since adopting Thunderbird.

Hence my post in this particular forum.

If you normally send using HTML you would see a Formatting Bar in the Write window which allows you to choose colours, make bold, italic etc. see image showing Formatting Bar below.

You can invoke Plain Text mode by holding down 'Shift' key when you click on 'Write'. but it will only be Plain Text for that particular email.

You can set it up so that particular people in your address will only be sent the Plain Text mode.

• Click on 'Address Book'
• select the address book which has that particular contact.
• double click on contact name to open Editing window.

On the 'Contact' tab:

• 'Prefers to receive messages formatted as' select 'Plain Text' from the drop down menu.
• click on OK

Then make sure you are sending emails in both HTML and Plain Text. Via 'Menu Bar' 'Tools' > ' Options' > 'composition' > 'General' tab or Via 'Mail Toolbar' 'Menu icon' > 'Options' > ' Options' > 'composition' > 'General' tab

• click on 'Send Options' button

Text Format

• select: 'Send the message in both plain text and HTML'
• click on OK
• click on OK

Now you can use 'Write' in HTML mode, knowing that if you select three contacts and one prefers Plain Text, then the system will send in HTML to others and Plain Text to that one specific person.

Thank for that.

I am pretty certain I had set ALL the accounts to to use plain vanilla text in the "Settings > Composition & Addressing" menu. Due to HTML in email being The Work of Stan.

But I have gone belt & braces & nominated the specific domain & also the individual as well as "text only" as you suggested above, just in case HTML is sneaking out somehow. HTML contamination was actually my first thought but as the messages don't get through I can't ask the recipient to check for me. We shall see what we shall see  :-)

Didn't get this trouble with VMS.  :-)

You could always look in your sent folder for the errant HTML. Thunderbird will default to HTML if you insert HTML elements thought paste in particular.

You are right. You can. And of visible HTML there is none.  :-)

As I said, HTML was my first thought. The reason I am still using The Bat is that one app needs to be able to send HTML attachments (OK, it does not NEED to but it keeps on re-setting it's defaults back to HTML) & I like to keep that segregated. When the Easter break is over I'll send another couple of e-mails & see what happens now I have tried to cover ALL the html bases  :-)

Have a good Easter.

And... Thunderbird STILL not sending messages that ALL my correspondents can receive. There are at least three for whom failure is consistent. The Bat still has no trouble sending to all three.  :-(