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Tables in Emails

Source: vignettes/tables-in-emails.Rmd
tables-in-emails.Rmd

The problem

mc_md_render() converts a single markdown file to HTML. But what if you need an R-generated table in the middle of your email? You can’t put R code in a plain .md file.

mc_compose()

mc_compose() takes any mix of markdown files, HTML strings, and kable objects and stitches them into one email body.

library(mc)

df <- data.frame(
  Site = c("Nechako", "Mackenzie", "Skeena"),
  Plugs = c(4000, 3000, 3000)
)

body <- mc_compose(
  "communications/intro.md",
  knitr::kable(df, format = "html"),
  "<p>Let me know if the numbers look right.</p>"
)

mc_send(html = body,
        to = "brandon@example.com",
        subject = "Planting site summary")

Each argument is resolved in order:

  • .md file — header above --- is stripped, body converted to HTML
  • kable/kableExtra object — converted to HTML via as.character()
  • HTML string — passed through as-is

All <table>, <th>, and <td> elements get border and padding styles injected automatically for Gmail compatibility.

Simple table with knitr::kable

The most reliable option. Clean HTML, minimal styling, works everywhere.

df <- data.frame(
  Site = c("Nechako", "Mackenzie", "Skeena"),
  Plugs = c(4000, 3000, 3000),
  Status = c("Confirmed", "Pending", "Pending")
)

knitr::kable(df, format = "html")
Site Plugs Status
Nechako 4000 Confirmed
Mackenzie 3000 Pending
Skeena 3000 Pending

mc_compose() adds border and padding inline styles to every cell.

Styled table with kableExtra

For colors, bold headers, or highlighted rows, use kableExtra::row_spec() and kableExtra::column_spec(). These add inline styles that survive Gmail’s CSS stripping.

library(kableExtra)

kbl(df, format = "html") |>
  kable_styling(full_width = FALSE) |>
  row_spec(0, bold = TRUE, background = "#f5f5f5") |>
  column_spec(1, bold = TRUE) |>
  column_spec(2, color = "#2c7bb6")
Site Plugs Status
Nechako 4000 Confirmed
Mackenzie 3000 Pending
Skeena 3000 Pending

Avoid bootstrap_options like "striped" or "hover" — these rely on CSS classes in a <style> block that Gmail strips. Use row_spec() with explicit background colors instead:

kbl(df, format = "html") |>
  kable_styling(full_width = FALSE) |>
  row_spec(0, bold = TRUE, background = "#f5f5f5") |>
  row_spec(seq(2, nrow(df), 2), background = "#f9f9f9")
Site Plugs Status
Nechako 4000 Confirmed
Mackenzie 3000 Pending
Skeena 3000 Pending

Scrollable tables

Large tables can be wrapped in a scrollable <div> using mc_scroll(). Gmail preserves the overflow CSS so these scroll in the email client.

Wide table (horizontal scroll) 

wide_df <- data.frame(
  Site = c("Nechako", "Mackenzie", "Skeena"),
  Plugs = c(4000, 3000, 3000),
  Season = c("Fall 2026", "Fall 2026", "Fall 2026"),
  Latitude = c(53.92, 55.34, 54.38),
  Longitude = c(-124.02, -122.97, -127.17),
  BEC_Zone = c("SBSdw3", "SBSmk1", "SBSdk"),
  Elevation_m = c(680, 700, 520),
  Stock = c("Local", "Transfer", "Transfer"),
  Nursery = c("PRT Vernon", "PRT Vernon", "PRT Vernon"),
  Crew = c("Alpine Reforestation", "TBD", "TBD"),
  Access = c("FSR 200", "FSR 440", "Morice West"),
  Prep = c("Complete", "Scheduled", "Not started"),
  Soil = c("Silty clay", "Sandy loam", "Clay loam"),
  Moisture = c("Subhygric", "Mesic", "Hygric"),
  Permit = c("Approved", "In review", "Not submitted")
)

cat(mc_scroll(knitr::kable(wide_df, format = "html"), direction = "wide"))
Site Plugs Season Latitude Longitude BEC_Zone Elevation_m Stock Nursery Crew Access Prep Soil Moisture Permit
Nechako 4000 Fall 2026 53.92 -124.02 SBSdw3 680 Local PRT Vernon Alpine Reforestation FSR 200 Complete Silty clay Subhygric Approved
Mackenzie 3000 Fall 2026 55.34 -122.97 SBSmk1 700 Transfer PRT Vernon TBD FSR 440 Scheduled Sandy loam Mesic In review
Skeena 3000 Fall 2026 54.38 -127.17 SBSdk 520 Transfer PRT Vernon TBD Morice West Not started Clay loam Hygric Not submitted

Long table (vertical scroll) 

set.seed(42)
sites <- c("Nechako", "Mackenzie", "Skeena", "Fraser", "Bulkley",
           "Stellako", "Endako", "Stuart", "Salmon", "Bowron")
long_df <- data.frame(
  Row = 1:50,
  Site = rep(sites, 5),
  Plugs = sample(100:500, 50, replace = TRUE),
  Survival_Pct = round(runif(50, 60, 98), 1),
  Height_cm = round(runif(50, 15, 85), 0)
)

cat(mc_scroll(knitr::kable(long_df, format = "html"), direction = "long"))
Row Site Plugs Survival_Pct Height_cm
1 Nechako 148 92.3 53
2 Mackenzie 420 67.2 53
3 Skeena 252 70.3 15
4 Fraser 173 91.5 40
5 Bulkley 327 86.3 58
6 Stellako 245 69.1 73
7 Endako 221 61.6 40
8 Stuart 148 65.3 44
9 Salmon 227 68.2 55
10 Bowron 402 78.2 56
11 Nechako 123 67.5 65
12 Mackenzie 426 87.3 43
13 Skeena 455 60.3 79
14 Fraser 188 74.3 82
15 Bulkley 264 79.5 31
16 Stellako 209 60.1 66
17 Endako 119 82.1 78
18 Stuart 469 66.0 57
19 Salmon 466 73.6 59
20 Bowron 486 84.5 81
21 Nechako 396 89.5 75
22 Mackenzie 188 81.4 56
23 Skeena 382 68.9 72
24 Fraser 208 63.4 23
25 Bulkley 104 63.3 69
26 Stellako 311 71.6 59
27 Endako 447 85.4 25
28 Stuart 459 60.0 21
29 Salmon 358 67.9 47
30 Bowron 413 95.5 70
31 Nechako 397 95.2 66
32 Mackenzie 123 87.9 72
33 Skeena 257 72.7 27
34 Fraser 398 79.6 81
35 Bulkley 498 88.3 36
36 Stellako 413 83.5 25
37 Endako 235 83.8 65
38 Stuart 391 68.3 38
39 Salmon 423 68.2 70
40 Bowron 245 74.8 43
41 Nechako 208 95.8 63
42 Mackenzie 447 96.6 69
43 Skeena 296 88.1 28
44 Fraser 103 87.9 17
45 Bulkley 325 80.4 24
46 Stellako 454 60.1 63
47 Endako 314 83.1 80
48 Stuart 344 91.8 54
49 Salmon 213 88.6 57
50 Bowron 361 77.2 29

Both directions 

set.seed(42)
both_df <- data.frame(
  Row = 1:30,
  Site = rep(sites, 3),
  Plugs = sample(100:500, 30, replace = TRUE),
  Survival = round(runif(30, 60, 98), 1),
  Height_cm = round(runif(30, 15, 85), 0),
  BEC_Zone = rep(c("SBSdw3", "SBSmk1", "SBSdk", "SBSwk1", "SBSmc2",
                   "SBSdw1", "SBSwk3", "SBSdk", "SBSmw", "SBSdw2"), 3),
  Elevation = sample(400:900, 30, replace = TRUE),
  Lat = round(runif(30, 53, 56), 4),
  Lon = round(runif(30, -128, -122), 4),
  Source = rep(c("Local", "Transfer"), 15),
  Soil = rep(c("Silty clay", "Sandy loam", "Clay loam", "Silt loam", "Gravel"), 6),
  Moisture = rep(c("Subhygric", "Mesic", "Hygric", "Subxeric", "Mesic"), 6),
  Fish = rep(c("Yes", "Yes", "No", "Yes", "No"), 6),
  Permit = rep(c("Approved", "In review", "Not submitted", "Approved", "Pending"), 6)
)

cat(mc_scroll(knitr::kable(both_df, format = "html"), direction = "both"))
Row Site Plugs Survival Height_cm BEC_Zone Elevation Lat Lon Source Soil Moisture Fish Permit
1 Nechako 148 60.3 34 SBSdw3 724 55.7576 -126.8728 Local Silty clay Subhygric Yes Approved
2 Mackenzie 420 67.9 73 SBSmk1 875 55.8877 -127.8255 Transfer Sandy loam Mesic Yes In review
3 Skeena 252 94.5 64 SBSdk 517 53.7006 -127.1857 Local Clay loam Hygric No Not submitted
4 Fraser 173 83.2 32 SBSwk1 529 55.1735 -123.9190 Transfer Silt loam Subxeric Yes Approved
5 Bulkley 327 74.4 18 SBSmc2 481 55.7109 -122.3911 Local Gravel Mesic No Pending
6 Stellako 245 76.6 25 SBSdw1 807 54.8104 -124.6970 Transfer Silty clay Subhygric Yes Approved
7 Endako 221 61.4 30 SBSwk3 768 54.8945 -124.3894 Local Sandy loam Mesic Yes In review
8 Stuart 148 97.0 49 SBSdk 801 55.8122 -126.8180 Transfer Clay loam Hygric No Not submitted
9 Salmon 227 76.4 29 SBSmw 724 55.5514 -124.7886 Local Silt loam Subxeric Yes Approved
10 Bowron 402 96.4 65 SBSdw2 509 54.7395 -126.9227 Transfer Gravel Mesic No Pending
11 Nechako 123 93.7 16 SBSdw3 759 55.4642 -125.2887 Local Silty clay Subhygric Yes Approved
12 Mackenzie 426 84.3 41 SBSmk1 838 53.3412 -126.0977 Transfer Sandy loam Mesic Yes In review
13 Skeena 455 96.9 51 SBSdk 695 55.2935 -127.3030 Local Clay loam Hygric No Not submitted
14 Fraser 188 83.5 15 SBSwk1 548 54.8708 -126.8834 Transfer Silt loam Subxeric Yes Approved
15 Bulkley 264 72.7 56 SBSmc2 883 53.4453 -123.6216 Local Gravel Mesic No Pending
16 Stellako 209 73.2 26 SBSdw1 456 53.2408 -125.5288 Transfer Silty clay Subhygric Yes Approved
17 Endako 119 75.1 40 SBSwk3 499 54.3922 -125.5157 Local Sandy loam Mesic Yes In review
18 Stuart 469 89.8 60 SBSdk 886 55.3381 -125.1181 Transfer Clay loam Hygric No Not submitted
19 Salmon 466 61.5 69 SBSmw 697 55.2006 -125.4350 Local Silt loam Subxeric Yes Approved
20 Bowron 486 88.5 54 SBSdw2 801 55.4517 -127.1811 Transfer Gravel Mesic No Pending
21 Nechako 396 85.7 31 SBSdw3 490 53.5105 -123.0519 Local Silty clay Subhygric Yes Approved
22 Mackenzie 188 66.5 21 SBSmk1 668 55.8342 -124.4462 Transfer Sandy loam Mesic Yes In review
23 Skeena 382 69.9 21 SBSdk 580 53.8809 -123.2336 Local Clay loam Hygric No Not submitted
24 Fraser 208 79.5 36 SBSwk1 453 53.4472 -123.3858 Transfer Silt loam Subxeric Yes Approved
25 Bulkley 104 85.7 62 SBSmc2 738 55.1581 -122.4917 Local Gravel Mesic No Pending
26 Stellako 311 97.3 15 SBSdw1 687 53.9723 -122.8242 Transfer Silty clay Subhygric Yes Approved
27 Endako 447 88.9 30 SBSwk3 607 55.3364 -126.0981 Local Sandy loam Mesic Yes In review
28 Stuart 459 81.5 80 SBSdk 645 54.1833 -126.4444 Transfer Clay loam Hygric No Not submitted
29 Salmon 358 92.3 80 SBSmw 459 55.0358 -123.5464 Local Silt loam Subxeric Yes Approved
30 Bowron 413 67.2 66 SBSdw2 684 55.3275 -123.5158 Transfer Gravel Mesic No Pending

The default max_height for vertical scrolling is "400px". Adjust with mc_scroll(..., max_height = "600px").

Full workflow 

library(mc)

sites <- data.frame(
  Site = c("Nechako", "Mackenzie", "Skeena"),
  Plugs = c(4000, 3000, 3000),
  Season = c("Fall 2026", "Fall 2026", "Fall 2026")
)

body <- mc_compose(
  "<p>Hi Brandon,</p>
   <p>Here's the current planting plan:</p>",

  kableExtra::kbl(sites, format = "html") |>
    kableExtra::kable_styling(full_width = FALSE) |>
    kableExtra::row_spec(0, bold = TRUE, background = "#f5f5f5"),

  "<p>Total: 10,000 plugs across three sites.</p>
   <p>Does this match what the nursery has available?</p>"
)

mc_send(html = body,
        to = "brandon@example.com",
        subject = "2026 planting plan — cottonwood plugs")

Scheduled send

Use send_at to send an email later. This works with mc_compose() and mc_scroll() — build the body now, send it when you want.

library(mc)

sites <- data.frame(
  Site = c("Nechako", "Mackenzie", "Skeena"),
  Plugs = c(4000, 3000, 3000),
  Season = c("Fall 2026", "Fall 2026", "Fall 2026")
)

body <- mc_compose(
  "<p>Hi Brandon,</p>
   <p>Here's the planting plan with a scrollable table:</p>",
  mc_scroll(
    kableExtra::kbl(sites, format = "html") |>
      kableExtra::kable_styling(full_width = FALSE) |>
      kableExtra::row_spec(0, bold = TRUE, background = "#f5f5f5"),
    direction = "both"
  ),
  "<p>Let me know if the numbers look right.</p>"
)

# Send in 30 minutes
proc <- mc_send(html = body,
                to = "brandon@example.com",
                subject = "2026 planting plan",
                send_at = 30)

# Or at a specific time
mc_send(html = body,
        to = "brandon@example.com",
        subject = "2026 planting plan",
        send_at = as.POSIXct("2026-02-24 09:00:00"))

# Check or cancel
proc$is_alive()
proc$kill()

On macOS, caffeinate prevents the machine from sleeping until the email sends. The laptop lid can be closed as long as power is connected. If the machine does sleep through the send window, a 5-minute grace period applies — past that the send is skipped to prevent stale emails firing.

All scheduled send outcomes (sent, skipped, failed) are logged to ~/.mc/send_log.txt and trigger a macOS desktop notification.