Do XML sitemaps need to be manually resubmitted every time they are changed?

[Jamie.Stevens]

I have been noticing lately that quite a few of my client's sites are showing sitemap errors/warnings in Google webmaster tools, despite the fact that the issue with the the sitemap (e.g a URL that we have blocked in robots.txt) was fixed several months earlier.

Google talks about resubmitting sitemaps here where it says you can resubmit your sitemap when you have made changes to it, I just find it somewhat strange that the sitemap is not automatically re-scanned when Google crawls a website. Does anyone know if the sitemap is automatically rescanned and only webmaster tools is not updated, or am I going to have to manually resubmit or ping Google with the sitemap each time a change is made?

It would be interesting to know other people's experiences with this

[BruceA]

Hi

We submit our xml site maps daily automatically anyway.  Leave a copy on the site to be crawled, but by submitting the site map it ensures that the Google Index is upto date without waiting for it to be crawled.

There are plenty of bolt on sitemap generators which will automatically send the sitemaps, without manual intervention.

Bruce