[horde] ActiveSync re-syncs every 15 seconds

[Lucas (wb7.eu)]

Hello,

I have a little problem with Horde Groupware Webmail Edition 5.2.22 and
ActiveSync 2.41.3. The backend says, that everything is up to date.

When using Outlook 2019, but also on my iPhone with iOS 13.3.1, it sometimes
happens that the devices keep syncing and syncing for a while. For example,
my iPhone says "Receiving E-Mails", than shows a timestamp for the last
e-mail receiving from about 30 minutes ago and restarts "receiving e-mails"
again. This happens for about 10 minutes and drains the battery.

The same thing happens in Outlook 2019: "Inbox is being synced" (or
"Posteingang wird synchronisiert" in German), with short breaks, for about
3-10 minutes.

Every 15 seconds appears the following in the ActiveSync log of the Outlook
client:

[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: INBOX, synckey: {5a207f65-78ec-43a9-aa69-476b00000000}7103
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Calendar:fRxzKnAs_boufjYeAsZDCnX, synckey:
{5a207f65-2e04-4293-9b4d-476b00000000}936
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: @Contacts@, synckey: {5a207f65-69fc-4641-9dac-476b00000000}745
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Sent, synckey: {5a207f65-66d8-4c67-9b13-476b00000000}427
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Tasks:ayQNmapPNpEOY5Zzn8cgIXR, synckey:
{5cdd8c9a-9a20-45db-80fd-4fb400000000}649
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Cronjobs, synckey: {5a207f65-c8b0-479c-a462-476b00000000}2150
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Security, synckey: {5aa2f65c-0570-4a7a-848a-4b6400000000}62
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Trash, synckey: {5a207f65-bd34-40b3-b867-476b00000000}56
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Mailfilter, synckey: {5a207f65-9f5c-4a14-bec0-476b00000000}332
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Archive, synckey: {5a207f65-8884-4cac-aa0f-476b00000000}3
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Demo-Mails, synckey: {5d9cb098-db4c-401c-8965-5f7400000000}2
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Hostmaster, synckey: {5aa2f65c-714c-4653-8d7e-4b6400000000}442
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Postmaster, synckey: {5aa2f65c-364c-4f88-9516-4b6400000000}16
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Spam, synckey: {5a207f65-2b40-4648-aa65-476b00000000}292
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Junk, synckey: {5c2e7a02-ad48-4708-89a7-337900000000}179
[21422][2020-03-22T00:37:21+01:00] INFO: COLLECTIONS: Initializing state for
collection: Calendar:OmFD9QM5fIYvS_rLbdL2JRe, synckey:
{5e76950e-60f8-4019-ae52-7e7b00000000}2
[21422][2020-03-22T00:37:21+01:00] INFO: ----------COLLECTIONS: Sleeping for
15 seconds.

The following appears in the iPhone ActiveSync log:

[4523][2020-03-21T15:57:54+01:00] INFO: COLLECTIONS: Initializing state for
collection: Calendar:fRxzKnAs_boufjYeAsZDCnX, synckey:
{5e727404-30dc-4135-a802-40cb00000000}9
[4523][2020-03-21T15:57:54+01:00] INFO: COLLECTIONS: Initializing state for
collection: Sent, synckey: {5e732156-2b2c-4c51-982b-480b00000000}35
[4523][2020-03-21T15:57:54+01:00] INFO: COLLECTIONS: Initializing state for
collection: Tasks:ayQNmapPNpEOY5Zzn8cgIXR, synckey:
{5e72740e-cbd8-42c6-bb50-51d300000000}13
[4523][2020-03-21T15:57:54+01:00] INFO: COLLECTIONS: Initializing state for
collection: INBOX, synckey: {5e732138-7b54-44ec-a8b0-480b00000000}488
[4523][2020-03-21T15:57:54+01:00] INFO: COLLECTIONS: Initializing state for
collection: Contacts:Vk84y7VHh3oPbFyy5Piz_6m, synckey:
{5e727403-345c-4f73-91b9-59a500000000}22
[4523][2020-03-21T15:57:54+01:00] INFO: ----------COLLECTIONS: Sleeping for
15 seconds.

Does anyone have an idea, whats wrong here?

Best regards,
Lucas