creds_envvar: Some variables need to be loaded with Sys.getenv from the .Renviron while others do not.

[hendr1km]

When using the creds_envvar() function in smtp_send(), I noticed an inconsistency in how environment variables are handled:

• For most parameters (e.g., user, host, port), I need to explicitly call Sys.getenv("VAR") to retrieve the values.
  

• However, for the pass_envvar parameter, I must pass the name of the environment variable as a string (e.g., "SMTP_PASSWORD").
  

If I mistakenly use Sys.getenv("SMTP_PASSWORD") for pass_envvar, it results in an error indicating that the variable does not exist, even though it does.

This inconsistency is confusing and not well-documented in the package documentation. It would be helpful if either:

• The documentation clearly explains this difference and provides examples.
  

• The function is updated to support Sys.getenv("VAR") for pass_envvar, aligning it with the behavior for other parameters.
  

smtp_send(
email = email,
from = Sys.getenv("EMAIL_USER"),
to = participant_mail,
bcc = Sys.getenv("EMAIL_USER"),
subject = "Content",
credentials = creds_envvar(
user = Sys.getenv("EMAIL_USER"),
pass_envvar = "SMTP_PASSWORD", # Must be the name of the variable, not Sys.getenv()
host = Sys.getenv("SMTP_HOST"),
port = Sys.getenv("SMTP_PORT"),
use_ssl = TRUE
)
)