D6 to D7: error in update #7201 when running update.php

Hi.

I'm upgrading a site from D6 to D7. In the site with D6, I had HTML MAIL 6.x-2.61. In the new site, I have 7.x-2.62.

When I was running update.php, I received these messages:

An unrecoverable error has occurred. Can you find the error message below. It is advised to copy it to the clipboard for reference.
Please go to the error page

AJAX HTTP Error Result Code HTTP: 200 These are the debugging information. Path:! Url Text Status: OK Response Text: Fatal error: Call to undefined function mailsystem_get () in C:\wamp\www\drupal\sites\all\modules\htmlmail\htmlmail.install on line 56

We can also see:

The update process was aborted prematurely while running update #7201 in htmlmail.module. All errors have been logged. You may need to check the watchdog database table manually.

Because of this error, the new site is inaccessible (we can not log in or access any other page).

Any ideas?

Tks.