The usage of Regardfully

Carefully instead of regardfully, if carefully describes the meaning you intend.

Hi roger,
Can I use regardfully to replace carefully?

I don't think so. What does regardfully mean? If I'm getting the meaning of your sentence, you might consider cautiously.

Hi roger thanks.
I also don't know what the meaning of regardfully is.

I had never heard of the word before in my life. According to online sources, it means respectfully or carefully. I'd advise not using it, you'd just get strange looks from native English speakers.

The word "regardfully" sounds like the name of a song that would be the signature song of a new Broadway musical. It would have to have a meaning that would only apply to the musical's story line. Perhaps, someone was not yet able to speak English correctly, and used the word "regardfully," and then the musical's cast would break into song, with the word "regardfully" being repeated a number of times in the song. In effect, shades of "The rain in Spain falls mainly on the plain." (My Fair Lady.)

http://onelook.com/?w=regardfully&ls=a