Send...whenever...maybe Rated 1 out of 5 stars

No longer impressive.

Since the most recent update, Send Later doesn't send at all. (Yes, everything required is updated, plugged in and turned on.)

The interface should allow direct entry of sending time. The drop-down menus for hour, minute, year, month, and day are far to slow and cumbersome.

A setting in milliseconds (see the option for "Check Every") makes no sense, except to a programmer. The setting needs to be in human terms--at minimum in seconds, although minutes makes more sense. (Let the machine do the conversion.)

The new colour scheme is garish. It may make things (arguably) clearer, but it's harder to look at, so the trade-off makes the change moot.

Update: A message just went though! Although, with a setting in milliseconds, 19 minutes between the "will be sent around" time and the actual time sent is too wide a gap to be considered "sent around."

This review is for a previous version of the add-on (3.3.9). 

Both agree and disagree

"Since the most recent update, Send Later doesn't send at all. (Yes, everything required is updated, plugged in and turned on.)"

This is a bug report / support request, which means that it doesn't belong here. My email address is on the add-on page, and I respond to emailed requests for support very quickly. If you need help solving a problem with the add-on, please email me. I can't engage in a support dialogue with you here.

Thousands of users of this add-on are using it to send scheduled messages every day, so if it's not working for you, the problem is probably specific to your environment. I will happily help you debug the issue if you get in touch with me by email.

"The interface should allow direct entry of sending time. The drop-down menus for hour, minute, year, month, and day are far to slow and cumbersome."

Version 4.0 of the add-on will allow free-form date/time entry. A beta release is available now at https://addons.mozilla.org/en-US/thunderbird/addon/send-later-3/versions/4.0beta1 if you want to give it a try.

"A setting in milliseconds (see the option for 'Check Every') makes no sense, except to a programmer. The setting needs to be in human terms--at minimum in seconds, although minutes makes more sense. (Let the machine do the conversion.)"

This will be fixed in version 4.0.

"The new colour scheme is garish. It may make things (arguably) clearer, but it's harder to look at, so the trade-off makes the change moot."

I've removed the blue color change in 4.0. It's no longer necessary because there are other UI improvements which make the buttons obvious without the color change.