Imagebuilder Chaos Calmer tl-wr841nd: Flashing dont happen?

I have flashed a TP-Link tl-wr841nd v7 with the factory image. I must send emails from the router through a gmail address. I thought of ssmtp, it needs libopenssl. But there is not enough space to install both. So I followed this tutorial to create my own image. I took tiny archiv and this Saving-Space-Tutorial to remove some packets. But the sysupgrade image is not created. I think its because of the image size, it dont fit into the router. So I took the ImageBuilder from 15.05 Chaos Calmer I created an image that suits my needs:
make clean ; make image PROFILE="TLWR841" PACKAGES="-ppp -ppp-mod-pppoe -opkg -ip6tables -odhcp6c -kmod-ipv6 -kmod-ip6tables -odhcpd-ipv6only ssmtp libopenssl uhttpd uhttpd-mod-ubus libiwinfo-lua luci-base luci-app-firewall luci-mod-admin-full luci-theme-bootstrap"

But if I flash the *wr841nd-v7-squashfs-sysupgrade.bin to the router, there is no ssmtp available, but the removed ppp and ip6 packets are still there. I think the flashing dont happen. So I took the precompiled CC sysupgrade image. Now OpenWRT 15.05 is running on the router. But if I try flashing again with my self compiled sysupgrade image, the ppp and ipv6 packets are still in the software list and no ssmtp. As next I took the example command from the Saving-Space-Tutorial for devices with only 4MB flash::
make clean ; make image PROFILE="TLWR841" PACKAGES="uhttpd uhttpd-mod-ubus libiwinfo-lua luci-base luci-app-firewall luci-mod-admin-full luci-theme-bootstrap -ppp -ppp-mod-pppoe -ip6tables -odhcp6c -kmod-ipv6 -kmod-ip6tables -odhcpd-ipv6only"

After flashing, the ppp and ip6 packets are still listed in Luci->Software->InstalledPackets

  1. Can you tell me what I'm doing wrong? If the created sysupgrade image is somehow broken then the flashing is aborted? Why cant I flash with sysupgrade images that I created with the ImageBuilder?
  2. What kind of checkum is used in Chaos Calmer in "Flash Firmware - Verify"? Its not MD5, SHA1 or SHA256. But I think this is not the problem.
  3. Is there an easier way to send emails through a Gmail address? One that used significant less space, so I could use a more recent release?
  1. You are using a device and firmware you found in a museum.
  2. Some old forgotten standard.
  3. Yea it is. Use a smartphone or a computer. You don’t need a router to send mail. Especially gmail that is googles webbmail system. So you only need a web browser in any computer with internet.