I accidentally addressed my lecturer as Mrs instead of Ms in an email.
Should I send a follow-up email explaining it was a typo or should I leave it be?
Since requested multiple times in comments: The lecturer does not hold a doctorate or any other academic titles. She also did not specify how she prefers to be addressed before.
I have heard from women (in mathematics departments, in the US) that they prefer not to be addressed as Ms or Mrs.
The issue is that some students address their male professors as "Dr." or "Professor" but their female professors as "Ms." or "Mrs." Perhaps you don't do this, but I would still recommend "Dr." or "Professor" unless your professor encourages otherwise.
Indeed, I know of one female professor who tells students that she is happy to be called "Dr. X" or "Professor X", and happier still to be addressed by her first name, but requests that her students avoid "Ms" or "Mrs".
It should also be added that this in the US, and cultural practices may be different elsewhere.
I don't think it's necessary to send a follow-up e-mail, but since you are worried about it, I think it would be perfectly polite to write something very brief like "p.s. How do you prefer to be addressed? Is Dr. X better?"
Leave it be; just be certain to be exactly correct in future messages. If she has a doctorate, she's "Dr. Familyname" in the U.S. and many other places. If she has academic rank, she's "Professor Familyname."
In most universities in the U.S., the title "Professor" is acceptable even for those without doctorate or academic rank.
Leave it be. Don't overthink it. Chances are that she didn't even notice. And if she did, it's highly unlikely that she'll hold a grudge if you correctly address her in future communication.
As others have pointed out, there is no consensus on what is the best way to address someone in professional communication. While many people prefer something as informal as "Hi {firstname}" (this includes people with a PhD or other academic title), others may be a lot more oldfashioned and consider that impolite. If you really feel insecure about how to address a person, it's therefore always better to ask him or her in person before you send your first mail.
Still, in my experience, there's a big discrepancy between how we're taught to communicate when we're young and how we end up communicating professionally once we're actually out there working 40+ hours a week in a real job that requires us to communicate with multiple people on different continents throughout the day. In the real world, people tend to be much less formal (and more focused on getting things done) than we're taught to be as youngsters. This includes professors and other academic staff. So as I said in the beginning : don't overthink it.
This cartoon captures it pretty well :
I have been seen academia in two countries: India and Netherlands.
In Netherlands, most professors are super busy and they really know that such a mistake was typo. In such cases, if you send an additional mail it just is one more mail for them to read. (They will still not be angry at you for doing so) Thus, you don't have to explain such a typo and correct yourself next time.
In India, almost most professors are busy. Above solution applies. But there are a few professors who take it personally and get offended if you do not address them 'Dr.'
(P.S: In both of the above countries, there is high probability that you might get to work with a professor whom you can address "Dear First_name,")
Don't worry about it. Most professors are both hardened in many senses by the stress in their everyday job and also have lots of duties so they can't let such silly things bother them. There is a fair chance he has not even seen your email if it did not have a course name in the subject line.
In Academia a professional title should be used as the primary form of address. Perhaps I am in the minority of people that had instructors without PhD. If your professor has PhD, then the mistake (according to etiquette of the majority) was not calling her "Doctor" or "Professor". For that, I personally would correct and apologize as it really can be received by the Professor as a significant lack of respect, and since that was not your intent then an apology is appropriate.
Likewise, non-PhD instructors should not be called "Professor" because that is a title one earns through their PhD completion and then progressing up the academic ranks, so is disrespecting of the Professors that have earned that title and rank.
Here is a list of academic ranks by country: https://en.wikipedia.org/wiki/List_of_academic_ranks
This has good info for addressing non-PhD instructors: How to address an academic without a PhD
For non-PhD instructors, I'd follow general business etiquette such as this: https://www.thebalance.com/when-to-use-miss-mrs-or-ms-3514830
Unless of course the instructor has instructed or voiced another preference.
If a Professor has said it is acceptable to call by first name, I would only do that in private one-on-one. If the Professor has said it is permitted in a class setting, I would do so as long as there are no peers or superiors of the Professor present.
Next time you have a reason to send her an email, add a sentence saying "I noticed that in my last email I mistyped 'Mr. X' instead of 'Mrs. X'; please accept my apology."
Also note that both honorifics may be wrong as @Anonymous suggests.
I cannot imagine she paid any attention to it, unless she should, by rights, be addressed as "Dr" or "Professor". I wouldn't bring it up. However, if it's really bothering you, or if she's already explicitly asked you (individually or as a group) to call her "Ms", you can briefly apologize the next time you see her. "Oh, by the way, I'm sorry I called you 'Mrs' in an email the other day. I know you prefer 'Ms' and I didn't realize until after I'd sent it."
Also, just as a data point, I prefer "Ms" even when using my husband's last name because I was raised according to some now-outdated social guidelines. One of those guidelines is that a woman is "Mrs [husband's first name] [husband's last name]", because "Mrs [woman's first name] [husband's last name]" is only used once he's dead.
