Email question for the tech guys

[Black Dog]

Is an underscore (_) a valid character as part of an email address? The guy in the business next to mine came over today to ask me how to email someone with that in their address. It seems that the underscore was either interfereing with the underlined (hyperlink?) email address or was not visible because of the underline. His mail server kept kicking it back to him but I don't know what kind of error message he was getting.

[joshua]

Shouldn't be a problem. It might be their mail client that doesn't like it. I have a yahoo account with underscores in it like that and have never had a problem using it.

[Wasch_24]

Trust me, the 1500 spam emails I get per week in my bulk folder on yahoo proves that the underscore is not a problem. :hysterica

[geoffrie]

Is an underscore (_) a valid character as part of an email address?
Yes, it is valid.

or was not visible because of the underline.
A reasonable concern in re humans discerning the underscore.

but I don't know what kind of error message he was getting.
This could help.

[PetersCreek]

It seems that the underscore was either interfereing with the underlined (hyperlink?) email address or was not visible because of the underline.
If he's clicking on an e-mail hyperlink which opens a new e-mail message with the address automatically inserted, I seriously doubt it's the fault of an underscore. In that case, I'd suspect an improper "mailto:" address in the web page code. He could right-click on the e-mail link, select Copy Shortcut, paste it into the e-mail To: field, and delete the "mailto:" portion, leaving only the address from the webpage code. If it still bounces, you can be pretty sure it's a problem with the addy or the receiving server.