Check settings in Tools>Preferences>Composition. Otherwise, I cannot duplicate your experience on this.

Thanks, but nothing to see in Composition, nor on account or globally. No spelling or anything funny. Just checked looking in local address books.

What to look for did you mean?

Typical would be addresses from address book not used for a couple of months or so. In the To field, just typing one letter I get 6 listed as counted.

Now using them since a week, they appear as expected.

But happend to a couple just today and last week, so felt something is wrong here. Number of them in list just diminish, to finally show none as I have the full email until '@' I know is unique, so still need to look up what domain and stuff.

re :Number of them in list just diminish, to finally show none Definitely weird.

Check this preference is selected:

• Menu app icon > Preferences
• Select 'Composition'
• Scroll to 'Addressing' section
• Select checkbox 'Local Address Books'

Alternative to typing in the 'TO' field..... In 'Write' do you ever use the 'Contacts Sidebar' ? Not visible? View > select 'Contacts Sidebar' You can select an address book to see list of contacts in that particular address book. Or you can select address book and then use the search to narrow it down. You can select/highlight one or more and then use the 'Add to' buttons or double click on a contact name to auto add to TO. More info: https://support.mozilla.org/en-US/kb/addressing-email#w_selecting-and-adding-recipients-from-contacts-side-bar

Thanks, I did write that it was checked Local Address Books. And checked to add to address book as you send to somebody, as well.

Thanks for the tip of workaround, kind of. But much smoother when it works as you are used to.

It got to be something about how many there are in address book where number of hits are more or less. I have not narrowed down completely. Just a theory.

Last one today was letter 'i', then 'n' and then 'g' and then there were nothing more shown. Even though Ingrid is there.

Another was 'm', 'a', 'r' and 'i' showed nothing, even though marie-louise and the rest is there.

Some logic fails it seems to me. So checked out if mentioned before. And there were some older threads on the topic, but closed ones. So staff does not want bumping old ones.

Came to think about one thing.

These two I had problem with last, I never typed manually before, so never used like this since having a conversation with them time ago. Then only doing reply to and such.

So typing these might be at the very bottom or something. It seems to be sorted according to use a bit.

Anyway, one thing that might help to track down....

re: Ingrid

Is 'Ingrid' in the 'Personal Address Book' ? If no, what address book? Is it one you created manually in the Thunderbird Address Book or an imported address book or a remote address book which you connect to eg: LDAP or use CardDav?

In the Contact details, does 'First' or 'Display' contain the text: Ingrid

In Collected Addresses is what I talk about. Automatically added as you reply to an email I think, since this is checked in preferences. Columns are Name and Email with any content. Both contain Ingrid och whatever I referred to.

There are 1232 entries in this Address Book.

There is one Address Book called Outlook Express which contain 24 entries, none of the search in this case. And a Personal Address Book with zero entries.

I think my last comment is on to something, there is some kind of resently used list I believe. And the ones only automatically added seem not to be searched since maybe not considered used not manually typing them in the To field.

But once fully typed, no help from Thunderbird, they work. Would be nice if looked up just being in an address book. Just a thought....