Desktop email clients are old technology.  I've been using gMail since it came out and wouldn't dream of using a desktop client based system to access my messages.  I have NEVER had a situation where gMail decided I didn't need to have a message so they deleted it.  It is the best spam filter in the industry and works on every platform available.  In the "old days" getting a new computer was a chore as one had to be very careful to make sure and backup all old messages and contacts and move them to a new machine. With cloud based systems this is a thing of the past.  Initially I was concerned that there wouldn't be enough storage space.  gMail uses a delete function and an archive function.  If you want to keep something long term simply archive it and it will never be deleted.  Deleted items go to the trash and are gone in 30 days.  I've only used 1/3 of my allotted free storage in the past 10 years.  The search function is fast and easy too.