What web service with the ability to set tasks via e-mail?

Question

Email

There is a team in different cities. We use Bitrix24. For tasks it turned out to be inconvenient. They are hidden inside the system (many clicks), the interface is bloated. The mobile app is not the fastest.
I'm looking for a web service (I have no place to put myself), which will:
* (!Important) the ability to set tasks by forwarding a letter;
* convenient mobile application. I would like the data to be synchronized at startup, but local. For example, Asana always shakes everything up: both projects and tasks. On slow Internet (3G) it makes you nervous
* Preferably with a Russian interface
Case: a letter arrives from a partner. I forward it to the employee with my comments. A task is set. Ideally, closing the task is also via mail. Or with one click (check the box in the web interface).
Can be paid.

Answer 1

Bitrix sends a letter and below it has a hash of the task itself, all other correspondence can be conducted from the mail, save this tag and everything will be attached to Bitrix.
In general, everything in Bitrix is ​​normal, just get used to it.
Megaplan doesn't even come close