Then it's a low fees issue, bitcoind on electrum servers is rejecting transaction due to low fees.
Just increase fees and try again or manually create and broadcast transaction but it can take some hours to some days, to get confirmations.
Ps: How big is your bulk transaction? I mean how many addresses?
So the transaction has 2 inputs and 29 outputs. I just now tried with a fee of 0.001 BTC and it still returns the exact same error. How much of a fee do you think would be appropriate?
It shouldn't be that much.
Inputs are ~200 bytes each.
Outputs are ~40 bytes each.
Your tx is something on the order of 2KB so even 0.2 mBTC (maybe 0.3 mBTC) should be sufficient. There is something else the server doesn't like about it. If you decode the raw tx and paste the json some people may be able to help otherwise I would verify all the inputs are valid and haven't been double spent. Verify all the addresses are valid and there is no duplicated address in the output. Verify the input = output + intended fee.