There is a facility to change the look of the 'Reply, Forward, etc' buttons. Try this: Right click on or near the buttons and select 'Customise'. Bottom left of window locate 'Show:' There are three options:

• Icons
• Text
• Icons beside Text

Select 'Icons' and it will use the least space. click on 'Done' to close window.

Thanks for answering, Toad-Hall. This helps showing all the buttons (I've had tried it before).

However I would still like to know if it's possible to increase the number of rows in the toolbar, or to add a second toolbar in the message pane area.

It is possible to add a new toolbar to the top toolbars and add all the 'Reply' 'forward' etc buttons onto that toolbar.

Via 'Menu Bar' 'View' > 'Toolbars' > 'Customise' or via 'Mail toolbar' 'Menu icon' > 'Options' > 'Toolbar Layout'

at the bottom, click on 'Add New Toolbar' then you add the buttons you require.

As this would be across the entire top of window, you might find it offers a better option.

The same methodology is not offered for the buttons/toolbar area in the Message Pane; only a choice of icon, text or both, which use varying amounts of space.

Thanks for replying once more, Toad-Hall. I ended up doing what you suggested: adding some buttons to a toolbar in the top. It's not perfect (I would have preferred the button in the message pane) but it does what I need.