Mozilla Thunderbird "On-The-Fly" Options
You will find on this page a series of seemingly unrelated tips in Thunderbird. It is the fact that they allow you to temporarily override Thunderbird's global options that binds them. It isn't as confusing as it sounds; please read on.
Forwarding an email
Depending on your preferences, emails are forwarded either inline (in the body of the forward email), or as attachments (the forwarded email appears as an attachment to a blank email).
Whether from Thunderbird's main window, or from an opened email window, use the Message > Forward as sub-menu to pre-select an inline or attached forward email.
Email Window Options
All the options described below are available under the Options menu, a new email window. Most of the application-wide ("global") version of these options are covered under Composition Options in Thunderbird, which we will assume you have read.
Invoke the Spell-Checker, Check Spelling as You Type
To invoke the spell-checker while writing an email, go to Options > Check Spelling.
Using Options > Spell as You Type, you can toggle on or off Thunderbird's on-the-fly spell-check feature, regardless of global options set under Composition > Spelling.
Ctrl+KCheck spelling
Quote Message
While not necessarily an "option", this feature is available under the Options menu; it allows you to replicate on top of your email the body of the email you are forwarding, or to which you are replying. It is lined on the left with a blue border, like the paragraph you are reading.
Return Receipt
Regardless of the global Thunderbird options you may have set under Composition > Addressing > Return Receipt, you can toggle the return receipt request setting on or off for the current email by using Options > Return Receipt.
Character Encoding
You can override Thunderbird's character encoding settings for an individual email by going to Options > Character Encoding. This will not affect your Display > Fonts settings.
Email Format
Regardless of global email formatting options, you can use the following formatting for a new email: Auto-Detect, which should accommodate your sender's format, Plain Text Only, Rich Text (HTML) Only, or Plain and Rich (HTML) Text. These choices are available under Options > Format.
Email Priority
Email priority is not a global options, and needs to be set for each email, (which makes sense). The default for Thunderbird and other email clients is "Normal", in other words, no priority information. Most email clients support 3 levels of priority: high, normal, and low. Thunderbird offers five: Highest, High, Normal, Low, and Lowest. Microsoft Outlook 2003, which supports three levels of priority, recognizes Thunderbird's High and Highest as High, which is good.
Email Security
Thunderbird offers the option to digitally sign and/or encrypt an email. We will cover email security for Thunderbird in an upcoming tutorial. Stay tuned!