Almost all email systems provide mechanisms for sending out "out of office" or "vacation" autoreplies and such mechanisms have been available for many years so shouldn't we all use them?
The short answer, with very few exceptions, is NO
To understand why these facilities should not be used, let's first consider the reasons why some might think that they're a good idea:-
You always respond to email right away, don't you? Doesn't matter what you were doing before, when an email arrives you stop what you're doing and attend to it. You don't even make any attempt at fitting it in with your other priorities, it goes straight to the top of your list and is dealt with immediately.
Conversely, when you want someone else to do something right away, you just email your request don't you? No need for a follow up phone call, the email will be perfectly adequate.
In my view, when sending email you should assume that it will arrive in a "reasonable" time and be dealt with in a "reasonable" time unless you have cause to know otherwise OR it matters. If it matters, you should always "assume the worst" and act accordingly. What that means depends on the nature and importance of the particular email.
If the email was sent by mistake or containing embarrassing material or wrongly addressed or whatever, assume that it got there immediately and was read immediately. Maybe you can stop or retrieve it, probably not!
If the email contains a vital, urgent, request, assume that it will get lost and just never arrive. Phone, write, visit - double check! don't just assume.
So, in my view, there's just no need for automatic notification of delay because, if the delay matters, the sender will chase; if the delay doesn't matter - well it just doesn't matter!
What does "professional" mean? Does it merely mean that you earn your living doing something or does it mean "superior", "educated", "expensive" or something along those lines?
Most people would mean the latter when they say "I want to convey a professional image" so let's consider what really professional people would do about correspondence during planned absences.
Incoming correspondence, whether by phone, fax, post or email, is usually a mixture of everything from straight junk through to vital contractual matter so the first stage in processing it must be to sort the "wheat from the chaff" - junk mail to the wastebasket, writs and cheques to the deal with now pile and so on. This process requires human not machine intervention. Yes you can do a fair bit of sorting by machine but the professional would make use of human skills. Professionals employ receptionists and secretaries.
When a professional goes on holiday, his secretary or receptionist or partner will handle incoming phone calls, faxes and paper mail and, if he's a real professional, emails as well.
If the professional has regular or predictable dealings with, say, important clients, he will have informed those people in advance of his anticipated absence and provided them with advice on how to proceed in his absence.
So, in my view, there's just no need for automatic notification to convey a professional image and it wouldn't anyway.
Not only are automatic replies unnecessary and unhelpful, there are good, positive, reasons weighing against their use.
Let's drop the 'e' from 'email'. Next time you go away, leave instructions for the most junior member of the mailroom staff, perhaps the work experience summer student, that he is to collect your mail from the mat and mail a standard reply back to each sender (regardless of who they are and what they want) and then put the incoming mail in a bucket to wait for your return.