ssmtp vs. Gmail

I am trying to setup my raspberry's ssmtp to use my Gmail account. I followed recommendations I found around, everything looks ok but the mail does not come. ssmtp.conf:

root=@gmail.com
mailhub=smtp.gmail.com:587
hostname=.ydns.eu
FromLineOverride=YES
AuthUser=@gmail.com
AuthPass=16charpassfromGoogle
UseSTARTTLS=Yes
UseTLS=YES

revaliases:

root:@gmail.com:smtp.gmail.com:587
pi:@gmail.com:smtp.gmail.com:587

actual command:

pi@raspberrypi:~ $ echo -e  "to: @gmail.com\nsubject: [RASPBERRY]\n\nTest 1...2...3" |  ssmtp -vvv @gmail.com
[] EHLO .ydns.eu
[] STARTTLS
[] EHLO .ydns.eu

close(4)                                = 0
getuid32()                              = 1000
openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 4
_llseek(4, 0, , SEEK_CUR)            = 0
fstat64(4, {st_mode=S_IFREG|0644, st_size=2307, ...}) = 0
read(4, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 2307
close(4)                                = 0
ioctl(0, TCGETS, 0xbef3b238)            = -1 ENOTTY (Inappropriate ioctl for device)
openat(AT_FDCWD, "/home/pi/dead.letter", O_WRONLY|O_CREAT|O_APPEND, 0666) = 4
_llseek(4, 0, , SEEK_END)          = 0
fstat64(4, {st_mode=S_IFREG|0644, st_size=657, ...}) = 0
write(4, "\n\n", 2)                     = 2
close(4)                                = 0
exit_group(1)                           = ?
+++ exited with 1 +++

What is it trying to do with /etc/passwd and what should I get from "Inappropriate ioctl for device" message? What do I miss?