If you are sending 'Direct messages' - meaning you are messaging freelancers directly from their PROFILES and not in response to a proposal submission, Upwork limits those types to 5 messages per day
https://support.upwork.com/hc/en-us/articles/360046621873-Direct-Messages-
"You can make up to 5 new connections via direct message per day."
The reason for this is that freelancers don't like 'spam' anymore than clients do: Lots of the job posts on this site are actual scams put up by scam artists pretending to be real 'clients'. If Upwork allowed client accounts to send an unlimited number of 'direct messages', scammers could simply just 'spam' messages to hundreds and thousands of freelancers instead of 'hoping' they 'apply' to their scam job post.
And, contrary to popular believe, not all freelancers even LIKE receiving those types of 'direct messages', even from legit clients, but since we freelancers have no way to 'turn off' the feature (which I have actually requested), I'm glad Upwork at least LIMITS how many messages that can be sent like that daily. I am not a fan of 'direct messages' because I don't like a client messaging me without having a CLEAR project description/job description laid out that I can read, and if they have something like that, they can just as easily put it in an 'invite-only' job posting where I can read over it and see if I'm interested or not. There are also clients that send 'direct messages' with no clear objective other than a social 'meet and greet' for 'networking' purposes, and not all freelancers have time for that or are interested in unexpected 'informal' chats with random people. Also, lots of the best freelancers are WORKING during the day, so constant 'one off messages' to discuss a big project can become disruptive: I'd rather a client take the time to get their 'thoughts together' and a plan of action for what they need, write it down, and then we can talk.
If you are referring to limits to messages you are sending after starting an interview with a freelancer in response to a proposal received to a job you posted, that's a different problem and likely a bug in the system you'll want to report to Support.
If you need to speak with lots for freelancers before hiring, your best bet is to simply create a job post and 'invite' the freelancers you wish to speak with. (You can make the job 'invite only' if you don't want random people applying). Then, you can search for and 'invite' freelancers to apply IF they are interested. This is the proper way to do it and is more respectful of the freelancers time, as messages "out the blue" can be disruptive, as I said.
The 'direct message' feature is intended to be used for clients needing to make special 'one off' connections to a freelancer that caught their eye when they don't have a job post yet written up, but I don't think Upwork intends that to be the primary means of hiring where all clients can just 'direct message' an endless number of freelancers 'out the blue' endlessly. There are likely hundreds of thousands of clients on this platform and if all of them were permitted to send an endless 'flood' of direct messages into our Inboxes, that would be a nightmare for us freelancers. I wouldn't be on UW much longer if they allowed that, personally. The 5 message limit encourages clients to use the privilege selectively.
