Can you also post the log that is appearing when you try to login?
DAVdroid is known to work with Posteo.
Did you try port :8443 like described on https://www.davdroid.com/tested-with/posteo/?
Also, please post the log that is appearing when you try to login.
I alread wrote that I also tried port 8443 but after my research I think 8443 is the old port and 8843 is the new one.
However, none of them works.
That’s the log when I try to login @ https://posteo.de:8843:
https://pastebin.com/4p9Es70Z
PS: As username I entered name@posteo.de but I also tried only “name” without @posteo.de.
Both didn’t work.
I think it is either it is a temporary issues with posteo (this occurs on a regular basis) or some other app like a firewall, privacy guard or antivirus is blocking the connection.
It is a clean phone where I did a factory reset today.
It’s working here with our test account (tries Login with URL and port 8843). Did you setup app-specific passwords or two factor auth with posteo?
Also try to change the network. Maybe your wifi router is blocking a connection.
I didn’t set an app-specific password or 2FA.
With the huawei mail client it works fine.
And the router doesn’t block anything.
On my other phone (Android 
it also works but with Mailbox.org account.
Does setting up mailbox.org work with your current huawei phone?
@devvv4ever said in DAVdroid + Posteo:
Does setting up mailbox.org work with your current huawei phone?
Yes that works.
Well, then I think I can’t help you any more… Must be a temporary connection problem with posteo, or you mis-typed something with in the login dialog, maybe the password?
https://posteo.de:8843
username@posteo.de + password
just worked for me…
I typed it 100% correctly since I’m using a password manager and this login works for website and mail client just fine.
Mh okay thank you anyway. I’ll try again tomorrow.
2018-06-17 20:20:29 1671 [HttpClient] <-- HTTP FAILED: java.net.ConnectException: Failed to connect to posteo.de/89.146.220.134:8843
This is a connectivity problem and probably not related to DAVdroid.
I tried mobile data and also WiFi.
I can’t access https://posteo.de:8443 and neither with port 8843 from my android device. It says ERR_CONNECTION_REFUSED in chrome.
But when I try to access it from my desktop chrome I get a login window.
When I enter my posteo credentials I’ll get:
This XML file does not appear to have any style information associated with it. The document tree is shown below.
<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
<s:exception>Sabre_DAV_Exception_NotImplemented</s:exception>
<s:message>GET is only implemented on File objects</s:message>
</d:error>
@psycho_bunny said in DAVdroid + Posteo:
I can’t access https://posteo.de:8443 and neither with port 8843 from my android device. It says ERR_CONNECTION_REFUSED in chrome.
Then this is a networking problem. It is not related to DAVdroid. You will have to find out why accessing posteo.de:8443 is not possible from your Android device.
I can access it from my other phone with Android 8.
As I said I made a factory reset on the Android 7 phone today. So this is a fresh installed Android 7 phone.
It isn’t possible for me to find out why I can’t access this site.
@psycho_bunny Unfortunately, I can’t help you in this case. 
You will have to find out why you can’t connect to this IP/port from your phone. I suggest to use the browser to test the connection. As soon as the connection works in the browser, it should also work with DAVdroid.
I had the same problem with DAVdroid and Posteo and found the cause, so I wanted to share this:
I am using LineageOS 14.1 on a GT-i9300 (Samsung Galaxy S3) in Austria, my mobile telecommunications operator is A1. As far as I remember I never edited the APN settings after setting up my phone, so I suspect that the default APN for this operator is wrong (sure it’s possible I edited the settings and can’t remember it…). The active APN was named “live!” and used a Proxy – and I ran into the problem described here.
After changing the APN to “A1” (settings with the name of my mobile telecommunications operator and without a Proxy) I can’t reproduce this issue. You can find all APN settings included in LineageOS on GitHub.
BTW, thanks for DAVdroid!!
