I tried to use Opera as an alternative email client for last 3 months. Now when I am in a fuss ...
I tried to backup & restore. Exported Inbox & Sent as mbs. Now deleted email account; and it erased everything.
When I restored, Opera Mail does NOT fetches any email. After importing my sent messages, it fails to fetch messages in INBOX.
Funny ... the most frustrating experience: Now, I just realized, no email client imports Opera emails ... ha ha ha ... Many tools online, but paid versions only ...
I would NOT recommend anyone to use Opera Mail Client.