1. Download and verify

Get the source tar ball and the corresponding PGP signature from http://sylpheed.sraoss.jp/en/download.html and verify your download by checking the signature. I have a directory called src/ inside my home directory where I put source files of software I want to build, so Sylpheed's sources will go there as well.

msi@devuan:~$ cd src/
msi@devuan:~/src$ wget http://sylpheed.sraoss.jp/sylpheed/v3.5/sylpheed-3.5.1.tar.gz http://sylpheed.sraoss.jp/sylpheed/v3.5/sylpheed-3.5.1.tar.gz.asc

As you probably won't have the public key corresponding to the signature available, you will get the usual error trying to verify it:

msi@devuan:~/src$ gpg --verify sylpheed-3.5.1.tar.gz.asc 
gpg: assuming signed data in `sylpheed-3.5.1.tar.gz'
gpg: Signature made Fri Jul 29 09:41:09 2016 CEST using DSA key ID C00C2E26
gpg: Can't check signature: public key not found

Get the key, using:

msi@devuan:~/src$ gpg --recv-keys C00C2E26
gpg: requesting key C00C2E26 from hkp server keys.gnupg.net
gpg: key C00C2E26: public key "Hiroyuki Yamamoto <hiro-y@kcn.ne.jp>" imported
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0  valid:   6  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 6u
gpg: next trustdb check due at 2019-06-08
gpg: Total number processed: 1
gpg:               imported: 1

Then verify the signature:

msi@devuan:~/src$ gpg --verify sylpheed-3.5.1.tar.gz.asc

Successful verification will look like this:

gpg: assuming signed data in `sylpheed-3.5.1.tar.gz'
gpg: Signature made Fri Jul 29 09:41:09 2016 CEST using DSA key ID C00C2E26
gpg: Good signature from "Hiroyuki Yamamoto <hiro-y@kcn.ne.jp>"
gpg:                 aka "Hiroyuki Yamamoto <yamamoto@sraoss.co.jp>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 8CF3 A5AC 417A DE72 B0AA  4A83 5024 337C C00C 2E26

2. Install build dependencies

Install packages required to build Sylpheed, running:

root@devuan:/home/msi/src# apt-get build-dep sylpheed

3. Build Sylpheed

Extract the tar archive and change into the newly created directory:

msi@devuan:~/src$ tar xfz sylpheed-3.5.1.tar.gz
msi@devuan:~/src$ cd sylpheed-3.5.1/

Building Sylpheed now is as simple as following the instructions given in the INSTALL file:

msi@devuan:~/src/sylpheed-3.5.1$ ./configure
msi@devuan:~/src/sylpheed-3.5.1$ make

(If you have more than one CPU you might want to use the ''-j'' option to speed things up (see "man make").)

msi@devuan:~/src/sylpheed-3.5.1$ su
Password:
root@devuan:/home/msi/src/sylpheed-3.5.1# make install

4. Install libsylph1

If you run Sylpheed from the command line after the installation, there will the following error message:

sylpheed: error while loading shared libraries: libsylpheed-plugin-0.so.1: cannot open shared object file: No such file or directory

This is due a missing package and thus easily cured. Just install libsylph1 and you're set:

msi@devuan:~/src/sylpheed-3.5.1$ su
Password: 
root@devuan:/home/msi/src# apt-get install libsylph1

(Btw, it's important to install this package after you've installed Sylpheed, for some reason.)

Run the program:

msi@devuan:~$ sylpheed

Source build and Devuan package

For me, building Sylpheed from source is an interim soultion until Devuan ASCII becomes stable. At that point I will upgrade my system and switch over to the distribution package.

To simulate the transition from the source build to a distribtuion package, I first uninstalled Sylpheed by running "make uninstall" in the source directory:

root@devuan:/home/msi/src/sylpheed-3.5.1# make uninstall

Then I installed the package version from the Jessie repositories and tried to use that. This worked flawlessly. As Sylpheed holds all personal data and configuration in a directory called .sylpheed-2.0 (that name should probably be changed upstream) inside your home directory, nothing will get lost, when you uninstall the program itself.

As I wasn't going to use the version from the repositories, I purged that package and then reinstalled the newer version built from source:

root@devuan:/home/msi/src/sylpheed-3.5.1# apt-get purge sylpheed
root@devuan:/home/msi/src/sylpheed-3.5.1# make install

This went well, but when I wanted to run Sylpheed I got the above error again, despite libsylph1 being installed. So I purged and reinstalled that package:

root@devuan:/home/msi/src/sylpheed-3.5.1# apt-get purge libsylph1
root@devuan:/home/msi/src/sylpheed-3.5.1# apt-get install libsylph1

Problem solved.

So, I suppose that if you uninstall Sylpheed before upgrading to ASCII and then install the distribution package after the upgrade, that won't cause any problems.