This update for Mozilla Thunderbird to version 45.4.0 fixes the following issues:
When using Thunderbird in a browser like context, for rendering HTML e-mail or feeds,
it may be affected by vulnerabilities also fixed in Firefox ESR 45.4. (MFSA 2016-86, boo#999701)
The following bugs were fixed in this release:
Display name was truncated if no separating space before email address
Recipient addresses were shown in wrong color in some circumstances
Additional spaces were inserted when drafts were edited.
Mail saved as template copied In-Reply-To and References from original email.
Threading broken when editing message draft, due to loss of Message-ID
'Apply columns to...' did not honor special folders