Reference

All functions
address()	Email Address
to() cc() bcc() from() reply() return_path() sender()	Add address fields to message
after(<envelope>)	Append children to message
as.address()	Create an address object
as.character(<MIME>)	Convert MIME object to character vector
as.character(<address>)	Convert address object to character
as.character(<envelope>)	Create formatted message.
as.character(<header>)	Create formatted header.
attachment()	Add attachments to a message object
c(<address>)	Concatenate address objects
cleave()	Split a compound address object
comments()	Add or query comments of message.
compare()	Compare vectors
compliant()	Tests whether an email address is syntactically correct
expires() replyby()	Set or query message expiry or reply-by time
display()	Extract display name
domain()	Extract domain of email address
encrypt() signature()	Encrypt or sign a message
envelope()	Create a message.
format(<address>)	Encode email addresses in a common format
html()	Add an HTML body to a message object.
keywords()	Add or query keywords of message.
length(<address>)	Length of address object
local()	Extract local part of email address
mime-parameters	Parameters for MIME functions
normalise()	Normalise email address
parties()	Extract sender and recipient(s)
priority() importance()	Add fields for message importance and priority
print(<address>)	Print an address object
print(<envelope>)	Print a message object
qp_encode() qp_decode()	Quoted-Printable encoding
raw()	Extract raw email address
request_receipt_read() request_receipt_delivery()	Request read or delivery receipts
render()	Render Markdown into email
inreplyto() references()	Add In-Reply-To and References header fields
sensitivity()	Set or query message sensitivity
server() gmail() sendgrid() mailgun() sendinblue() mailersend() mailfence() zeptomail() smtpbucket()	Create a SMTP server object.
subject()	Add or query subject of message.
template()	Add message body from template
text()	Add a text body to a message.
validate()	Validate email address