[FIX] fix bug with standard emails sending

[cvinh]

When installing mail_statistics_extras, we cannot send standard emails anymore

There was a typo, here is the fix

[rafaelbn]

cc @janetrp @antespi @JavierIniesta

[rafaelbn]

@antespi please review and update PR in OCA

[antespi]

Thanks @invitu, good point!! ;)

[cvinh]

Hello
I think that commit has not been merged with OCA/social branch...

[rafaelbn]

Done. @antespi lost you change somewhere, sorry.

[cvinh]

finally, the code has been rewritten
mail = super(MailMail, self).create(vals)

so you can return mail

[cvinh]

I did a PR on OCA/social branch