Lost emails during akonadi database rebuild

HI

Due to my kmail (Version 5.3.0 (QtWebEngine)) crashing at will every few 
minutes (and akonadi server had its restart issues last week), i thought i'd 
clear out the akonadi database and let it all rebuild from scratch in the hope 
it might help kmail. I did the following (i followed this link https://
docs.kde.org/stable5/en/kdepim/kmail/clean-start-after-a-failed-migration.html 
- which may have been the wrong thing to do):- 

Akonadictl stop
~/.local/share/akonadi
~/.config/akonadi
akonadictl start

I've now got a load of emails back but only starting from about May this year 
and i should have had emails going back years. The lost emails are not an 
issue because its just mailing list stuff but i was under the impression that 
the akonadi database was separate from the emails so i should not have lost 
any. Was this an incorrect belief?

Regards
Ian

-- 
Qt: 5.6.1
KDE Frameworks: 5.25.0
kf5-config: 1.0
KDE Plasma: 5.7.4
Kernel: 4.7.2-1-default
"openSUSE Tumbleweed"