[GekkePrutser]

I used past tense because he stopped his blog/mailing list ;) At least in the form I used to read it.

But I agree that 'used to use' would be a better form without this connotation. I will strive to use this in the future in such cases.

He used to have a monthly mailing list, and I wasn't sure whether he still had a blog or something.

[tzs]

One problem with 'used to use' is many might take it as implying that he now uses something different. Perhaps 'has used' would be better?