Trying to get GroupWare's Evolution to show the time and date in the mail listing window pane in the way that I wanted has been a pain, simply because you have to discover the variables in a trial-and-error method. I can't find a list anywhere (for Evolution). I don't know if they're following a Linux standard, or their own (there seems to be a mixture). Some of the explanations I've included below are from the date command, and will require longer testing to see if Evolution is following them or doing its own thing.
This is what I've discovered with Evolution3.28.5 on CentOS 7 in July 2024, organised into the components of calendar, time, and timezone; then preformatted strings for date & time; and lastly (weird) numerical day and week numbers. (Weird, as in people start counting the first day or week of the year from one, not zero.)
| Variable | Function | Example |
|---|---|---|
| %a | short dayname (locale format) | Fri |
| %A | long dayname (locale format) | Friday |
| %ad | short relative day or dayname | Today, Yesterday, or Fri |
| %d | numerical day of the month (zero padded) | 19 |
| %e | numerical day of the month (space padded) | 19 |
| %m | numerical month of year (zero padded) | 07 |
| %b | short month name (locale format) | Jul |
| %h | short month name (same as %b) | Jul |
| %B | long month name (locale format) | July |
| %g | year (short format) of ISO week number (see %G) | 24 |
| %y | year (short format) in normal human usage | 24 |
| %G | year (long format) of ISO week number (for %V) | 2024 |
| %Y | year (long format) in normal human usage | 2024 |
| %C | century (first two digits of %Y) | 24 |
| %H | hours (24-hour clock, zero padded) | 10 |
| %I | hours (12-hour clock, zero padded) | 10 |
| %k | hours (24-hour clock, space padded) | 10 |
| %l | hours (12-hour clock, space padded) | 10 |
| %M | minutes | 51 |
| %S | seconds | 15 |
| %p | AM/PM (uppercase or locale format?) | AM |
| %P | am/pm (lowercase) | am |
| %z | timezone (numerical) | +0930 |
| %Z | timezone (by initialised name) | ACST |
| %r | time locale 12-hour clock format (zero padded) | 10:54:15 AM |
| %R | time 24-hour clock (%H:%M) | 10:54 |
| %T | time 24-hour clock (%H:%M:%S) | 10:54:15 |
| %X | time locale 24-hour clock format | 10:54:15 |
| %D | date numerical (%m/%d/%y aka American format) | 07/19/24 |
| %F | date numerical (%Y:%m:%d aka library/ISO format) | 2024-07-19 |
| %x | date locale format | 19/07/24 |
| %c | locale time & date | Fri 19 Jul 2024 10:54:15 ACST |
| %n | new line (not practically useful) | |
| %t | tab (not practically useful) | |
| %w | numerical day of week (0–6, Sunday = 0) | 5 |
| %u | numerical day of week (1–7, Monday = 1) | 5 |
| %U | week number of year (00–53, week beginning Sunday) | 28 |
| %V | ISO week number of year (01–53, week beginning Monday) | 29 |
| %W | week number of year (00–53, week beginning Monday) | 29 |
| %j | day of year (001–366) | 201 |
| %s | epoch timestamp (seconds since 1970-01-01 00:00:00 UTC) | 1721353318 |
NB: Locale examples are showing what I see in my locale. If you're not in South Australia, expect to see how times and dates are usually written in your locale. Of course this depends on how you've set up your computer preferences, it's not fully automatic. I'm guessing that some are locale settings, rather than simply string presets, because they match other locale styles. And I'm not changing my system settings, nor mis-setting my clock, to test this.
I set my variables in Evolutions mail header preferences thus: %A %e-%b-%Y %l:%M %P
To see: Friday 19-Jul-2024 10:54 am
I've skipped variables that produced no obvious result (null or blank spaces).
Removing all the variables just produced a short numerical time and date display in the local format, with the today/yesterday date replacements for mail from today or yesterday.