I recently noticed that the signature block is usually dropped after the first message sent by anyone in an email correspondence.
Is this standard convention? Is it safer to always include a sign-off, or does this risk being too formal?
I would definitely suggest dropping them after the first email from a given participant. In fact, many email clients and even some mail servers have automatic features to do just that.
Email chains can get rather long, regardless of whether they are "formal" or not. Once you have a signature in the thread their job is done. After that they are noisy and clutter up the thread with redundant and mostly uninformative content. This is especially true for signatures with photos and large, fancy fonts.
A smaller signature is usually sufficient once things are going. Example:
Sam Smith, Company, Site Operations Coordinator
There are cases where I would make an exception: when you are requesting to be contacted directly, or a response may be needed through channels other than email. In those sorts of situations I would add the signature back in, manually if necessary.
Yes, it is perfectly acceptable to drop the longer signature and use a shortened version to sign off. Something like:
-- I use is to indicate to the compatible email server / clients to identify that the remaining part is a signature, so if there is a capability to hide the signature part (even the shortened one) by default, it gets hidden.
The use and contents of a signature block has lately been directed by corporate policy. The company I work for has specified that the signature block appear in both new messages and replies. They have dictated the information they want us to include in our signature block.
Other than corporate policy there is no standard. Some never include a signature block, others only on new messages, and others on every message.
My preference has developed of time to use as compact a block that meets the corporate policy, and include it on all messages. It is frustrating when you are added in the middle of the chain and a key person early in the chain didn't include their email/phone in a signature block because their message was a reply.
Does this risk being too formal?
The risk isn't so much that you'll come across as too formal. Using reasonable formality is generally always the safer bet when communicating in the workplace.
The risk is that this is unreasonable formality. The formality in itself isn't the problem - it's that you're using it inappropriately and excessively, and it's getting in the way of communication.
This is about email, but the lesson to take from this is broader: the somewhat arbitrary protocols of formality are fine in measure. Using them shows professionalism, mutual respect, and manners. But if you start letting them get in the way of getting work done, it flips, and it's not a good look at all. It comes off unprofessional, inefficient, perhaps even incompetent if taken to extremes.