Missing random E-Mails and slow Sync on Yahoo

Hello,
I’m using IMAP and SMTP for my Yahoo-Mail.

However, I do have the problem that random mails are not downloaded from the servers main inbox. This is rare (maybe 1 in 500), but I cannot figure out what is the problem.
For example from a conversation of 5 E-Mails one is not downloaded/shown.
Other clients and yahoos website show and download the E-Mail just fine. This happens for various senders and independently whether an attachement is used or not.

Additionally, syncing takes very long, rarely finishing at all.
Any thoughts or troubleshoots?

Additionally, syncing takes very long, rarely finishing at all.

I use a Yahoo.com account and have the following Yahoo IMAP settings in the screenshot below that seem to work fine for me. So first check your account “mail server, port and security policy” are correct.

The missing emails might be in your spam / junk folder. So check their if you haven’t already.

Also check eM Client rules via “Menu / Rules” in case you have possibly accidently setup rules to block or move Inbox specific sender emails to any folders. Dbl-click any rules & the blacklist to see inside them. You could even try unchecking everything in rules including the spam filter to test.

Now if you have no rules setup & disabling all rules made no difference and nothing in the spam / junk folder, then try removing and re-adding your Yahoo account via the automatic email wizard setup in “Menu / Accounts”. Could be some account problem within eM Client when the account was prev setup.

Now if removing and re-adding the account makes no difference, then could be you might have some optionally installed program interfering with eM Client. eg: If you have any optional firewall / security program, or optional Antivirus program or VPN, try completely disabling those to test.

Non of your suggestions work.

Settings just like yours, no rules enabled. Mails are not moved/within junk.
Re-Adding account has no effect, as well as disabling anti virus.

Next then go to “Menu / Show Operations” via the dropdown next to “Refresh” at the top left and then click on the far right “Log tab”. Then look for any obvious errors in the log and paste them in this thread.

18:03:49 Online state: changed to online due to NetworkAvailability 
18:03:49 [email protected] CalDAV Synchronizing account properties: For host https://caldav.calendar.yahoo.com/.well-known/caldav
18:03:49 [email protected] CardDAV Synchronizing account properties: For host https://carddav.address.yahoo.com/.well-known/carddav
18:03:49 [email protected] IMAP Synchronizing folder list
18:03:50 [email protected] CardDAV Synchronizing account properties: Done
18:03:50 [email protected] CardDAV Synchronizing folder list
18:03:51 [email protected] CalDAV Synchronizing account properties: Done
18:03:51 [email protected] CalDAV Synchronizing folder list
18:03:51 [email protected] CalDAV Synchronizing items: For folder [email protected]
18:03:52 [email protected] IMAP Uploading item(s) to folder '/Inbox'
18:03:52 [email protected] CalDAV Synchronizing items: Sync of [email protected] finished: 0 uploaded, 0 deleted, 0 obsolete, 0 items,  0 downloaded
18:03:[email protected] CalDAV Synchronizing items: Done
18:03:52 [email protected] CalDAV Synchronizing items: For folder [email protected]/XXX
18:03:52 [email protected] CalDAV Synchronizing items: Sync of [email protected]/XXX finished: 0 uploaded, 0 deleted, 0 obsolete, 0 items,  0 downloaded
18:03:52 [email protected] CalDAV Synchronizing items: Done
18:03:52 [email protected] CalDAV Synchronizing items: For folder [email protected]
18:03:52 [email protected] CalDAV Synchronizing items: Sync of [email protected] finished: 0 uploaded, 0 deleted, 0 obsolete, 0 items,  0 downloaded
18:03:52 [email protected] CalDAV Synchronizing items: Done
18:03:53 [email protected] IMAP Synchronizing folder '/Inbox'

No more entries until 18:15, but still the refresh icon is cycling…
No errors

Cannot see anything wrong in that part of the log.

Reading other Yahoo’s threads where they were only getting random Yahoo emails & slow synching, some found using the following alternative Yahoo server address “export.imap.mail.yahoo.com” fixed the problem. So maybe try putting export in front of your Yahoo IMAP server setting.

Others found that disabling “Mailshield” or real-time “Antivirus scanning of email” (within their Antivirus program) was the cause and fixed the issue by disabling that part.

Apart from that try updating to the latest eM Client version via the release history page for Windows & Mac V9.2.1557 if you haven’t already.

There was an update in the prev V9.1.2109 which included the new Yahoo API update which fixed any synching issues with the program, so if you were using an older version then that could be why you have been having slow synching issues apart from any Antivirus “Mailshield” scanning issue.

Note: Backup eM Client before updating via “Menu / Backup” You can see when the backup is complete via “Menu / Operations” in the dropdown next to refresh at the top left.

I am also getting this problem recently. All other emails (Outlook and Gmail) sync fine except for Yahoo. It sometimes won’t receive a specific email. The operation is also stuck on syncing the /Sent folder. Removing and adding the Yahoo Mail account back does not fix the issue.