I have some difficulties when moving from gmail as SMTP (limit is set to low for our site) to our own mail server which is whole new sience...; but after a month or so when other mail servers recognise our mail server as a legite one (reputation) no mail from our domain goes to SPAM.....; so there was some work and effort needed but we manage to stay independent from other services which always find the way to somehow limit you or they always want more and more money......