When you get an error message about your Endicia pass phrase, the problem is most likley on the Endicia side of things, not in Nexternal. Here are our suggestions:
First, do the following:
Have an Endicia agent enter a “permanent” pass phrase into your Endicia account.
Then in your Nexternal OMS, go to Settings/Compatible Software/Online Shipping Tools/Endicia Label Server/Manage/Edit passwords/synchronize pass phrase...and check "EDIT pass phrase". Select the "Synchronize Pass Phrase" option and enter the permanent pass phrase there. Do NOT reset the pass phrase. Then hit submit.
This should solve the problem. If it does not, you may have to open a new Endicia account, close the current account, and re-integrate the new account into Nexternal.
Leave reset as is.