After working fine for a while, since a couple of months our tablet cannot send mails from mail accounts across several providers. However, receiving mails works. I tried whatever I could think of or found on the internet (see below), and I am quite desperate... This page shows several possibly related questions, but they do not describe my problem.

It says "sending ..." -> Error message "senden fehlgeschlagen" = sending did not work. Update: Sometimes (seems random, possibly because it is shown for short time ~ 1 sec) it also says in addition "Server nicht verfügbar" = server not accessible (although internet and smtp server work when tested from the other devices, see below).


  • Samsung Galaxy 10, 2014 edition Android 5.1.1, Safety patch 2017-04-01 (i.e. all regular updates offered for it)
  • has enough memory > 6 GB free
  • mail client: standard Android mail client
  • mails are managed via IMAP (not POP3) / SMTP

Mail providers tested:

  • web.de (2 accounts from 2 people)
  • mail.de
  • tested each time with only one single account set (and all others removed), just to make absolutely sure the do not interfere with each other

What DOES work is the following:

  • sending (and every else) mails from each of the accounts using a) another android device (Samsung Galaxy phone, Android 5.0.1 - i.e. all regular updates offered for that device), b) PC/Thunderbird, and c) webmail.
  • send & receive mails via POP3. I wish to use IMAP (PORT numbers adjusted, same settings exp. for outgoing (SMTP) server).
  • internet bandwidth (45 MBit/s download, 6 Mbit upload, ping 92 ms) and volume

What I tried so far, without success:

  • shut down and restart the device
  • double-check mail account settings (incoming: imap.web.de / imap.mail.de, SSL, port 993, optional imap path prefix: none; outgoing: smtp.web.de / smtp.mail.de, TLS, port 587, "Anmeldung erfordern" = need authentification checked in checkbox, same PW). All is set as suggested by the respective providers, and as set in the other android device from which I can send mails.Tried also alternative settings (e.g. SMTP: port 25, and other settings), but this did not improve anything (even though probably not all possible combinations)
  • Removed and re-created the accounts (only one at a time). Still can receive, but not send.
  • Tried another WiFi at a friend's home, different telecommunication provider, same problem. There is no problem with bandwith, internet volume etc.
  • Tried on multiple days since several weeks to months
  • Mail app is updated
  • I prefer the normal android client. To our knowledge, there is no other (possibly interfering) client installed.


  • As suggested in comment below (thanks!): deleted all data and deleted all cache from mail app (and again deleted and re-created account) - no change.

  • No certificates are needed, but the mail provider requests the users to specifically allow mail clients (mail clients/apps in general, i.e. management via IMAP/POP3, as opposed to the provider's web surface). This option has always been and is still chosen (doublechecked, and works from other devices).

Thanks in advance, I am looking forward to your help.

  • 2
    Try clearing data for the mail app. Settings>apps>mail>storage>clear data. This will delete all the data that's saved in the app. But any data that's already in the cloud is not going to be deleted – aBochur Dec 26 '17 at 22:45
  • @Abochur: Thanks, hope I got this right, menu seems a little bit different. Went to settings > apps > E-Mail: delete all app data, and delete all app cache. Unfortunately id not help. Updates list in my question to keep anoverview. – Martin Dec 27 '17 at 8:38
  • @beeshyams: sorry - what do you mean by "chat the cache"? I cleared the cache, without improvement. – Martin Dec 27 '17 at 8:39
  • +1, good point - my work mail does, but not these free mail providers used on the tablet. Updates list in question accordingly to keep track... – Martin Dec 27 '17 at 9:33
  • I've also recently had email behave really oddly. Early December, out of nowhere it suddenly ate up 4 GB of my mobile data limit (which was 3GB), and it seems that things I emailed since then never arrived or arrived weeks late. I also found an email from last summer in my outbox. Honestly, this behaviour is so bizarre and broken that I'm inclined to consider the app broken en look for a better one. – mcv Jan 7 '19 at 17:35

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