imapbackup VS iRedMail

In terms of backup you could do incremental backups, example here in python - not tested by me personally but seems good.

If you want it totally DIY https://github.com/rcarmo/imapbackup and then any flat text search.

Check this out, you can use it with bridge https://github.com/rcarmo/imapbackup

If you have access to the server you could make backups on that end (that is what we where doing) if you dont have access to the server you would need to login to each mailbox to create the backup i suppose. Dont know which tools are good for that but i found this one it might help: https://github.com/rcarmo/imapbackup

There are loads of imap backup options from a quick search, such as https://github.com/rcarmo/imapbackup

Handling lots of production email for hundreds of domains for the past 10 years on https://www.iredmail.org/

If you have a better solution, for example a good provider who offer agency packages which allows many domains and there is no catch, for example very small disk space, then hit me right away. Otherwise, please share your experience with hosting your own mail service. I found https://mailinabox.email/ and https://www.iredmail.org/ for example, but never had any experience with neither of them.

I use iRedMail

iRedMail : https://www.iredmail.org/ good for samll companies and teams (the free version still serve but with no send limtes)

Last suggestion is to use iredmail and maybe iredadmin-pro (paid) for mailbox servers. It's a roll-your-own solution but so long as you are very detail oriented, strict with policies, use change management, and use something like ansible, it can really help this email stack scale. Also would help with #4.

Developed by iRedMail team: https://www.iredmail.org/

iRedMail. Free to use and basically trouble-free for me after some initial issues got worked out on my config.

Or host your email server. There is even services like r/VirtualMin & r/Webmin plus others like Mail-in-a-Box or iRedMail