365 email on ADSL , 10 users

Hi

I'm in the planning stage of moving a company from a problematic pop3 email provider to 365 Business Email (365 Exchange)

They only have ADSL, no fibre available and I assume no VDSL available~Modem~ dsl connects at 10M down, .8M up .ADSL Speedtests this morning were so slow it often timing out due to internet speed issues , if speedtest finishes the upload speed is so low its unusable. Shutting down all the PC's & restarting the dsl router bought the speedtest back up to approx .6Mbs upload .

So , the question is , at what stage do would you say the internet is just too slow to move emails to 365 ?Email Downloads shouldnt be an issue, but email send & sync could be when (available) upload speed drops too low.On the other hand, their current email setup has to send anyway, so would it really make no difference if they used current smtp or move to 365

Is ADSL just really too slow in general for 365 exchange for approx 10 users ? Either way , they need to change email provider .