I've been happily running Dovecot on my Mac for many years (installed via Homebrew). After upgrading to Monterey (MacOS 12.01), it no longer starts:
$ sw_vers
ProductName: macOS
ProductVersion: 12.0.1
BuildVersion: 21A559
$ uname -a
Darwin dfelicia-mac 21.1.0 Darwin Kernel Version 21.1.0: Wed Oct 13 17:33:23 PDT 2021; root:xnu-8019.41.5~1/RELEASE_X86_64 x86_64
$ sudo dovecot -F
Oct 27 10:11:18 service(log): Fatal: setrlimit(RLIMIT_DATA, 268435456): Invalid argument
$ mount
/dev/disk1s2s1 on / (apfs, sealed, local, read-only, journaled)
devfs on /dev (devfs, local, nobrowse)
/dev/disk1s5 on /System/Volumes/VM (apfs, local, noexec, journaled, noatime, nobrowse)
/dev/disk1s3 on /System/Volumes/Preboot (apfs, local, journaled, nobrowse)
/dev/disk1s6 on /System/Volumes/Update (apfs, local, jour
naled, nobrowse)
/dev/disk1s1 on /System/Volumes/Data (apfs, local, journaled, nobrowse)
$ sudo dovecot -n
# 2.3.16 (7e2e900c1a): /usr/local/etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.16 (09c29328)
# OS: Darwin 21.1.0 x86_64 apfs
# Hostname: dfelicia-mac
default_internal_group = mail
default_internal_user = _dovecot
default_login_user = _dovenull
first_valid_uid = 100
listen = 127.0.0.1
log_path = /var/log/dovecot.log
mail_location = maildir:/usr/local/var/mail/%u
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext
namespace inbox {
inbox = yes
location =
mailbox Drafts {
special_use = \Drafts
}
mailbox Junk {
special
_use = \Junk
}
mailbox Sent {
special_use = \Sent
}
mailbox "Sent Messages" {
special_use = \Sent
}
mailbox Trash {
special_use = \Trash
}
prefix =
}
passdb {
args = login
driver = pam
}
protocols = imap
service imap-login {
inet_listener imap {
address = 127.0.0.1
port = 143
}
inet_listener imaps {
address = 127.0.0.1
ssl = no
}
}
ssl = no
userdb {
driver = passwd
}
$ ulimit -Ha
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) unlimited
file size (blocks, -f) unlimited
max locked memory (kbytes, -l) unlimited
max memory size (kbytes, -m) unlimited
open files (-n) unlimited
pipe size (512 bytes, -p) 1
stack size (kbytes, -s) 65532
cpu time
(seconds, -t) unlimited
max user processes (-u) 2784
virtual memory (kbytes, -v) unlimited