Server says 5.7.1 Authentication failed

My emClient has always been very slow to sync/refresh with my Yahoo email, usually waiting up to 15 minutes while status shows “connecting”. However, now I am getting a message saying “Server says 5.7.1 Authentication failed”. This is POP3, and I’m able to see and reply to current emails from my PC and phone. Any clues on how I might troubleshoot this?

First thing to check is that you have the correct login name and password for your account. Go to Menu > Tools > Accounts and click on the General tab for that account. Under Authentication, make sure you have entered the same details as you use on your phone.

Then go to the POP3 tab and make sure that the port is 995 and the security policy is Use SSL/TLS on special port (legacy). Under Authentication, select Use identity credentials.

Then go to the SMTP tab and make sure the port is set to 587 and the security policy is Force usage of SSL/TLS. Under Authentication, select Use identity credentials.

Thanks Gary. I confirmed all of the above… Username / PWD correct, POP3 and SMTP settings correct. Anything else you can suggest?

I don’t know about Yahoo! but some other free providers like GMail have settings in the web interface to enable POP3. Also Google has a less secure app setting that needs to be enabled in order to use POP3. Maybe Yahoo! has similar settings.

Do you think deleteing the database or re-installing the emclient would help? If I reinstall, should I use the BACKUP/RESTORE? Or should I rebuild it from scratch? I have all my old emails archived in folders.

Reinstalling will not make any difference if there is some configuration issue. You would need to delete the database. 

With POP3 if you delete the database, you will most likely lose all your messages. Always make a backup (Menu > File > Backup) before doing anything drastic.

Better would be to export your messages first, then if the new database is working OK, import the message back into that.

Thank you. Can you please remind me how we delete the database? Also, I have a pretty large number of emails in my Yahoo inbox, more than 50,000. Do you think this is why emclient is very slow on my end? My emclient inbox is only a couple of thousand emails.


Here’s what I did:

  1. Deleted my emclient database.
  2. Restarted emclient, which saw this as a complete new install.
  3. After initializing questions, status showed as NEVER SYNCED
  4. I hit REFRESH F5 to begin syncing and it was trying to re-download my entire web inbox, which I did not need. Also, there was no progress showing. 
  5. To stop this, I selected FILE > WORK OFFLINE
  6. I did a FILE > RESTORE from my recent Backup. 
  7. I closed emclient
  8. I opened up YAHOO MAIL on my web. I had 60,000+ emails since 2013.
  9. I moved all of them (except for the past 3 days) to my ARCHIVE folder
  10. I restarted emclient, and it synced relatively quickly with only the past 3 days of emails.

SO… I guess the moral here is that the web INBOX can get problematic to sync with if it is too big.

I am not familiar with Yahoo!, but I wonder what will happen when eM Client gets to syncing the Archive folder?

Strangely, my em client neither shows nor syncs with any archive folder. The archive folder is only visible on my PC and on my phone. I think Yahoo intended it to be just a non syncing folder for storage…???